MOPOP - Chapter 14

Unity of invention
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Unity of invention

Table of Contents

14.01 Scope of this chapter

The Canadian Patent Act and Patent Rules are based in part on the simple premise of one patent for one invention.1 The concept of unity of invention refers to the requirement that an application claim one invention only. This requirement serves, in part, to ensure that the fees paid by applicants are fairly assessed on a per invention basis.

Requiring that a patent relate to one invention only also provides a measure of clarity to the patent system, by constraining the scope of individual patents. A patent specification directed to a single invention is clearer and more readily understood than one that attempts to describe and define several.

The present chapter deals with the subject of unity of invention from two perspectives. First, the assessment by an examiner of whether or not, for the purposes of examination, an application claims more than one invention, and with the procedures for dealing with an application that does and second, the framework and requirements for the filing of a divisional application to protect an invention other than the invention to which the claims of its parent application are limited.2 The term “parent” is used to refer to an application that describes more than one invention, and which served as the basis for the filing of a further application (a “divisional” application) to protect an invention other than the one ultimately claimed in the parent.

Note that throughout the chapter the term “invention” is used to refer to subject-matter that an applicant alleges to be an invention (an “alleged invention”). Where, when assessing unity of invention, an examiner identifies a plurality of inventions in a claim set, this should not be taken as a suggestion that all of the several inventions thus identified have been assessed for patentability.

14.02 Unity of invention

The basic framework that governs unity of invention is section 36 of the Patent Act, which provides that

(1) A patent shall be granted for one invention only but in an action or other proceeding a patent shall not be deemed to be invalid by reason only that it has been granted for more than one invention.

Unity of invention has been referred to as “essentially a procedural matter”,3 as it does not of itself give rise to issues of validity. Section 36 of the Patent Act also sets out provisions whereby the claims are to be limited to one invention only and any additional inventions described (or described and claimed, as the case may be) may be protected by the filing of separate and distinct applications therefor. Thus

(2) Where an application (the “original application”) describes more than one invention, the applicant may limit the claims to one invention only, and any other invention disclosed may be made the subject of a divisional application, if the divisional application is filed before the issue of a patent on the original application.

and

(2.1) Where an application (the “original application”) describes and claims more than one invention, the applicant shall, on the direction of the Commissioner, limit the claims to one invention only, and any other invention disclosed may be made the subject of a divisional application, if the divisional application is filed before the issue of a patent on the original application.

As discussed in the following sections, it is important to approach the concept of unity of invention bearing in mind its legal context and purpose, and not to confuse it with the determination of whether or not one invention is “the same” as another such as is done, for example, when assessing novelty or double patenting and during re-issue proceedings.

14.03 Meaning of “one invention only”

In interpreting section 36 of the Patent Act, the term “invention” in the expression “one invention only” is best understood as having a broad meaning. The broad interpretation of the meaning of the term “invention” in section 36 of the Patent Act is reflected in section 36 of the Patent Rules, which provides that

For the purposes of section 36 of the Act or of the Act as it read immediately before October 1, 1989, an application does not claim more than one invention if the subject-matters defined by the claims are so linked as to form a single general inventive concept.

In interpreting the scope of section 36 of the Patent Act, the Courts have ascribed to the term “invention” a meaning different than that provided in section 2 of the Patent Act.4 The Courts thus spoke of claims to matter in different categories of invention as being “aspects of a single invention”. A similar, broad interpretation of the meaning of “invention” has been ascribed by the Courts in considering other provisions of the Act.5 It is clear that the Courts have considered that the legislative intent of section 36 of the Patent Act is not fulfilled by interpreting the expression “one invention only” by giving the term “invention” its definition from section 2 of the Patent Act. That is, section 36 of the Patent Act should not be understood to say where an application (the “original application”) describes and claims more than one new and useful art, process, machine, manufacture or composition of matter […], the applicant shall […] limit the claims to one invention only […].

Thus, as directed by section 36 of the Patent Rules, an application will not be considered to claim more than one invention if the subject-matters defined by the claims are so linked as to form a single general inventive concept.

14.04 Canadian unity standard harmonious with PCT standard

The 1996 revision of the Patent Act and Patent Rules had as one of its objects the harmonization of the Canadian patent framework with the Patent Cooperation Treaty standards.6

This can be readily appreciated by comparing the language of section 36 of the Patent Rules with that of section 13.1 of the Regulations Under the PCT, which states that

The international application shall relate to one invention only or to a group of inventions so linked as to form a single general inventive concept (“requirement of unity of invention”).

The phrase “one invention only” in section 36 of the Patent Act, when understood in its full context and in view of section 36 of the Patent Rules (as discussed in 14.03), has a meaning equivalent to “one invention only or to a group of inventions so linked as to form a single general inventive concept” in Rule 13.1 of the Regulations Under the PCT.

The result is that the Canadian unity of invention requirement is not “different from or additional to” that provided for in the Patent Cooperation Treaty. Identifying a defect arising from non-compliance with the requirements of section 36 of the Patent Act does not contravene article 27(1) of the PCT.7

14.05 General inventive concept

Assessing whether or not unity of invention exists in a given claim set amounts to determining, having regard to the specification as a whole, whether or not a “single general inventive concept” exists to link the claims.8

The inventive concept can be identified by considering the purpose of the invention. The claimed invention should provide a solution to a practical problem, and claims that define that solution or refinements to that solution (or of how it is to be put into operation or manufactured, as the case may be) may all relate to a single inventive concept. Generally, a set of claims will share a general inventive concept if a set of new and unobvious elements is common to each claim in the set, provided the elements in question are those required for the proper operation of the invention in its broadest aspects.

The inventive concept relates to how a result is obtained (i.e. to the inventive aspects of a practical solution to a problem), and not simply to the idea of obtaining the result per se. The correct standard to consider is that of unity of invention (i.e. unity among the solutions to a problem), rather than “unity of result”. Mutually unobvious means (practical forms) for achieving a given result will generally not share a single general inventive concept.

The PCT expresses the concept similarly, in Rule 13.2 of the Regulations Under the PCT, which states that

Where a group of inventions is claimed in one and the same international application, the requirement of unity of invention referred to in Rule 13.1 shall be fulfilled only when there is a technical relationship among those inventions involving one or more of the same or corresponding special technical features. The expression “special technical features” shall mean those technical features that define a contribution which each of the claimed inventions, considered as a whole, makes over the prior art.

The expression “special technical features” used in the PCT Regulations refers to novel and unobvious elements of the claims that are responsible for the proper operation of the invention.

14.06 A priori and a posteriori evaluation

Claims that have in common a set of new and unobvious elements [as described in 14.05] satisfy the requirement for unity of invention.

The two aspects of the unity of invention requirement can be considered separately as: 1) the need for a common set of elements among the claims, and 2) the requirement that the common set of elements be new and unobvious (i.e. inventive) over the prior art.

The former can be assessed without regard to the state of the art, and is referred to as an a priori evaluation of unity of invention, whereas the latter requires the state of the art to be considered and is referred to as an a posteriori evaluation. A lack of unity of invention is a defect in an application regardless of whether it is identified a priori or a posteriori.

A typical approach for assessing whether the claims have unity of invention is to identify the claim with the fewest elements, and then check to see if those same elements appear in all the other independent claims. The claims may appear to lack unity of invention a priori where no claim defines solely those elements that are common to all the claims, however the absence of such a claim is not determinative since there is no requirement that there be one claim broader than all others, nor that there be only one independent claim in each category of invention [see 14.08.02 for additional guidance on this point].

In assessing whether a common set of elements is present, the language of section 13.2 of the Regulations Under the PCT should be borne in mind - that the claims must include “the same or corresponding special technical features”. The concept of “corresponding” means that two claims can have unity of invention even if they do not share a set of precisely identical elements, but rather share equivalent elements whose roles in the context of the invention correspond.9

Any prior art relevant for a determination of anticipation or obviousness under section 28.2 or 28.3 of the Patent Act may be considered in assessing whether unity of invention exists [see chapter 15 of this manual].

Example 1:

[This example sets forth an a priori analysis.]

An application discloses a paint containing a rust-inhibiting substance X, a process for applying said paint with substance X and an electrode arrangement A for applying paint. The electrode arrangement is useful for applying paint in general, and is not required in order to apply the paint comprising substance X (the benefits of having substance X in the paint are unrelated to how the paint is applied).10

Claims:
  1. A paint comprising a rust-inhibiting substance X.
  2. An apparatus for electrostatically charging atomized particles, comprising an arrangement of electrodes A.
  3. An apparatus for electrostatically charging atomized particles, comprising an arrangement of electrodes A, wherein said apparatus is for applying the paint of claim 1.
  4. A process for painting an article, said process comprising the steps of
    1. atomizing the paint of claim 1 using compressed air;
    2. electrostatically charging the atomized paint using an electrode arrangement A; and
    3. directing the paint to the article.

Analysis: An a priori assessment of the claims reveals two alleged inventions: the paint comprising substance X and the apparatus including electrode arrangement A. The special technical feature of claim 1 is substance X. The special technical feature of claim 2 is electrode arrangement A. Substance X and electrode arrangement A do not cooperate in any way. Claim 4 includes the technical features of both claims 1 and 2. Claim 3 makes reference to the technical features of both claims 1 and 2, but it must be determined whether the reference to the paint of claim 1 implies a practical limitation to the structure of the apparatus. If the apparatus of claim 2 is suitable for painting the paint of claim 1 (as it seems to be, in view of claim 4), then claim 3 defines the same apparatus as claim 2 and would lack unity of invention with claim 1 despite the reference to that claim.

There is an a priori lack of unity between claims 1 and 2, since the two claims do not share a technical feature in common. Unity of invention does exist between claims 1 and 4 (on the basis of the paint comprising substance X) and between claims 2, 3 and 4 (on the basis of the electrode arrangement A).

Note that while claim 4 can be included in an application with either claim 1 or claim 2, if it was maintained in the parent and filed in a divisional application the result would be double-patenting. Therefore, the subject-matter of claim 4 may be included in the claims of the parent or of the divisional, but not both.

Example 2:

[This example sets forth an a posteriori analysis.]

The application describes a computer monitor comprising elements A and B, and further discloses that additional elements C and D lead, respectively, to particular advantages.

A search of the prior art reveals document D1, which discloses a computer monitor comprising elements A and B.

Claims:
  1. A computer monitor comprising elements A and B.
  2. A computer monitor according to claim 1, further comprising element C.
  3. A computer monitor according to claim 1, further comprising element D.

Analysis: The claims meet the requirement for unity of invention on an a priori assessment, since elements A and B are common to each claim. In view of D1, however, these elements do not provide a general inventive concept that links the claims. To the extent that elements C and D have each been disclosed in the application as leading to particular, mutually unobvious advantages, claims 2 and 3 are directed to distinct inventions that lack unity of invention a posteriori.

If, on the other hand, it is clear to the examiner from the description and/or the prior art that features C and D do not provide inventive solutions to any practical problem facing the art (and are therefore not the result of further invention over the matter of claim 1), such that D1 renders claims 2 and 3 either anticipated or obvious, then only the consequent defects under sections 28.2 and/or 28.3 of the Patent Act should be identified. No defect under section 36 of the Patent Act should then be identified, although the examiner may note the potential lack of unity that might exist once the prior art defects are addressed [see 14.07.03].

14.07 Examining for unity of invention

The Office takes the position that the intent of subsection 36(1) of the Patent Act is that where an application describes and claims more than one invention, the claims require amendment so as to define one invention only. A lack of unity of invention among the claims is identified as non-compliance with subsection 36(1) of the Patent Act and the applicant is notified of the defect and requisitioned to correct it or to submit arguments as to why the claims do comply with section 36 of the Patent Act. This notification is made in an examiner's report issued under subsection 30(2) of the Patent Rules.

Given that, where a lack of unity of invention has been identified, the examiner cannot be certain which invention the applicant will elect to maintain in the claims, a report identifying non-compliance with section 36 of the Patent Act need only identify this defect. This is an exception to the usual requirement that a requisition under subsection 30(2) of the Patent Rules be based on a comprehensive examination [see section 13.05 of this manual]. In this sense, addressing a question of unity of invention can be viewed as a procedural matter to be resolved separately from the substantive examination of the application.

Where the applicant responds to a requisition identifying a lack of unity of invention by amending the claims in such a manner as to overcome the defect, this determines for that application the one invention only referred to in subsection 36(2) of the Patent Act [see 14.03]. Thereafter, any other invention disclosed may be made the subject of a divisional application. The Office takes the position that, in accordance with subsection 36(2) of the Patent Act, the claims of the original application [see 14.11] under examination may no longer be directed to the matter of any other invention disclosed. In responding to an examiner's report identifying a lack of unity of invention, the applicant effectively has the right to elect, one time only, the identity of the one invention only that will be the subject of examination in a given application.

Claims resulting from post-election amendments will generally be permissible in the application if they would have had unity of invention with the claims to the one invention only elected by the applicant.

To avoid prolonged debate over unity of invention, where an examiner considers that the claims lack unity of invention and the applicant declines to limit their claims to a single invention, the examiner may refer the application to the Commissioner of Patents for a determination of the issue. Typically, such a referral will not occur until the examiner has advised the applicant of the defect in at least two reports.

This referral will not take the form of a Final Action, since:

  • (a) should the applicant limit the claims to one invention only in response to a Final Action, subsection 30(5) of the Patent Rules would require the examiner to withdraw the rejection; this should generally result in allowance of the application, but in the case of a lack of unity of invention the claims would generally not have been fully examined; and
  • (b) should the Commissioner conclude after a review in accordance with subsection 30(6) of the Patent Rules that the application does not comply with subsection 36(1) of the Patent Act, no further amendment of the application would be possible in view of section 31 of the Patent Rules.

Where a review of the application [see 14.07.06] leads to the conclusion that the application complies with section 36 of the Patent Act, the examiner will resume prosecution and consider all the claims on file.

Where the Commissioner reviews the application and has reason to believe that it does not comply with section 36 of the Patent Act, a letter will be sent to the applicant directing that the claims be limited to one invention only. This direction will be made under authority of subsection 36(2.1) of the Patent Act, and is not a requisition under section 30 of the Patent Rules.

Where the applicant's amendments in response to the letter make the application compliant with section 36 of the Patent Act, examination of the application will continue. If the applicant's amendments in response to the letter fail to satisfy the Commissioner that the application complies with section 36 of the Patent Act, the application may be refused under section 40 of the Patent Act.

14.07.01 Content of the report

Whenever a report is written that identifies lack of unity of invention as a defect, an indication must be included in the report of the extent of the search and examination performed on the application as a whole.

As noted in 14.07, a report identifying a lack of unity may be limited in scope to address only that defect. This will usually be the case where a lack of unity is identified at the outset of prosecution. Where a lack of unity is identified later in prosecution, the facts of the case may be such that it is more efficient to identify this defect in parallel with a comprehensive examination of some or all of the claims, rather than interrupting the substantive examination in order to deal with the unity of invention defect alone.

Even where a lack of unity of invention is identified as a defect at the outset of prosecution, if the examiner believes (for example, in view of corresponding patents issued in other jurisdictions) they know which group of claims an applicant will elect for prosecution, they may include in their report an identification of all the defects associated with these claims. The choice of the examiner does not replace the applicant's right to make their one-time election [see 14.07]. If the applicant elects a different group of claims for prosecution from the one the examiner chose to examine, prosecution proceeds on the basis of the claims elected by the applicant.

Where there are defects in the application that affect the determination of unity of invention, an examiner may refer to these defects in addition to or instead of the lack of unity defect and should set out how the other defects impact the assessment of unity of invention or vice versa. Defects such as lack of clarity in the claims, or prior art that leads to a conclusion of a posteriori lack of unity of invention are illustrative of the types of additional defects whose resolution may impact the determination. To avoid confusion as to the necessary response by the applicant, it may be preferable to identify such defects informally (e.g. in the preamble of the report, or by otherwise explicitly indicating that the defect is not being formally identified), solely to explain the impact they had on assessing unity of invention.

14.07.02 Explaining a lack of unity defect

A report identifying a lack of unity of invention should explain the basis for the conclusion in a manner that will enable the applicant to decide whether and how to limit or divide their claims for further examination. This explanation should identify what the examiner considers the various distinct inventions to be, and should provide sufficient detail so that the applicant can understand why the different inventions do not share a single general inventive concept. Where the defect is identified a posteriori, the prior art supporting this conclusion should be cited in the report and an explanation of the significance of each document should be provided.

Wherever possible, the individual inventions identified should be related to the claims in which they are defined, so that the applicant can group their claims into sets which would be viewed by the Office as sharing a single general inventive concept. This will generally be done in all cases unless attempting to relate each invention to a specific claim or claims would only introduce a lack of clarity into the explanation of the defect. Other than in exceptional cases, the examiner will set out groups of claims that are considered to be directed to one invention only. When creating such groups, the examiner should clearly indicate to which group each independent claim belongs. Unless an explicit indication has been made by the examiner with respect to a given dependent claim, the applicant may presume that a dependent claim belongs to the group in which the claim it refers to is found.

Where a lack of unity exists among the alternatives defined in a single claim, the examiner will, to the extent practical, separate the various inventions into groups. In such a case, unless otherwise indicated by the examiner, a dependent claim belongs to the group in which the alternative it refers to is found.

As a general rule, if the applicant limits the claims in the application to one group of claims identified by the examiner, the application will be considered to have been made compliant with section 36 of the Patent Act. Certain exceptions to this general rule exist, however, such as where a further lack of unity of invention subsequently becomes apparent in view of prior art discovered after the applicant has elected a group of claims for prosecution.

Note that in identifying the various inventions in a claim set, the term “invention” is used as a matter of convenience only, and in no way implies that the subject-matter of any given claim is patentable.

14.07.03 When a lack of unity defect can be identified

In general, a lack of unity of invention should be identified in the first report written in respect of the claims that lack unity of invention.

In some cases, an examiner may identify defects in an application that bear on the question of whether the claims have unity of invention (e.g. obviousness, ambiguity, lack of utility or of support). Where the applicant's response in respect of the other defects is germane to its evaluation, it is permissible for the lack of unity of invention defect to be formally identified in a later report. Whenever possible, the applicant should be advised that the other defects bear on the question of unity of invention.

Since unity of invention is assessed in view of the claims of the application, a lack of unity of invention may be introduced when amendments are made to the claims. Where a lack of unity of invention is introduced by the applicant with an amendment, an examiner may identify the resultant defect regardless of the length of prior examination of the application.

Where prior art raises the possibility of a posteriori lack of unity, but some of the claims in the application are considered by the examiner to be anticipated or obvious in view of the cited prior art, it may be preferable to not identify the lack of unity of invention as a formal defect until the prior art defect has been addressed by the applicant. The applicant's response to the prior art defect may advance the examiner's understanding regarding unity of invention. The examiner may draw the applicant's attention, informally [see 14.07.01] and depending on the circumstances, to the potential unity defect.

If the applicant responds to a prior art objection by amending the claims, and the claims as amended appear to avoid the cited prior art but to lack unity of invention, an examiner may identify the lack of unity defect.

14.07.04 Responding to a requisition

As with any requisition sent under subsection 30(2) of the Patent Rules, an applicant may respond to the identification of a lack of unity of invention by amending the application (in order to comply with subsection 36(1) of the Patent Act) or by submitting arguments as to why the application already does comply.

Where the applicant amends the claims by limiting them to claims falling within a single group identified by the examiner, the lack of unity defect identified in the issued report will be considered to have been overcome in respect of those claims [see 14.07.02].

Should the applicant agree that there is a lack of unity of invention among the claims, but disagree as to the grouping of claims set out by the examiner, they may respond to the requisition by identifying groups of claims different from those identified by the examiner and electing one of those groups of claims.

Where the applicant's response to the requisition does not serve to make the claims compliant with the requirement for unity of invention, a further report identifying the lack of unity defect may be sent.

14.07.05 Election of an invention

The applicant will be considered to have elected an invention whenever, subsequent to a report in which a lack of unity of invention was identified as a defect, the applicant limits the claims to fewer inventions than were defined in the claim set with respect to which the lack of unity of invention was identified. It is not necessary for the applicant to explicitly state that they have “elected the invention of Group A” when making an election (although this may certainly be done by the applicant, in the interest of greater clarity).

Where the applicant's initial election limits the claims to a single invention, this defines the one invention only referred to in subsection 36(2) of the Patent Act [see 14.07].

Where the applicant initially elects more than one group of claims identified by the examiner, or claims belonging to more than one group of claims identified by the examiner, or even submits new claims entirely, any further election that may be necessary (i.e. should the initially elected claims still lack unity of invention) must be made from among the inventions defined in the initially elected claim set.

14.07.06 Referral to the Commissioner of Patents

As noted in 14.07, where an examiner considers that the claims lack unity of invention and has notified the applicant of this conclusion, but the applicant declines to limit their claims to a single invention, the application may be forwarded to the Commissioner of Patents for a determination of the issue.

Resolving questions of unity of invention should be conducted efficiently, since the substantive examination of the application is delayed by this procedure. Consequently, if an applicant has been notified of a lack of unity of invention defect in at least two reports they should expect that a referral to the Commissioner could be made without further notification.

To ensure consistency and fairness, where an examiner considers that an application should be referred to the Commissioner, they must first submit the application for review by a Unity Review Board (URB). This board will review the application in order to ensure the lack of unity defect was correctly identified and clearly articulated to the applicant, so that the applicant was in a position to successfully respond to the examiner's requisition.

Where the URB considers that unity of invention exists, the examiner will proceed with the substantive examination of all claims on file.

Where the URB considers that a lack of unity of invention exists, but that further clarification of the matter is necessary (e.g., further reasons for concluding a defect exists, or additional information regarding the identity of acceptable claim groups), the examiner will issue a further report taking into account the observations of the URB.

Where the URB considers that a lack of unity of invention exists, and has been clearly communicated to the applicant in an examiner's report such that the applicant could have responded successfully to the examiner's requisition, the application will be forwarded to the Commissioner of Patents for consideration.

Where the Commissioner considers it appropriate, the applicant will be directed to limit the claims under authority of subsection 36(2.1) of the Patent Act. A Notice of Direction will then be sent to the applicant by the Commissioner.

Where the applicant's response to the Notice of Direction does not satisfy the examiner that the application complies with section 36 of the Patent Act, the application will be forwarded to the Patent Appeal Board for a final review. At this stage, the process resembles the review of a Final Action [see chapter 21 of this manual], given that the Patent Appeal Board may recommend that the Commissioner refuse the application under section 40 of the Patent Act. In accordance with subsection 30(6) of the Patent Rules, an application will not be refused without the applicant being given an opportunity to be heard.

14.08 Specific guidance

The following sections provide more specific guidance on assessing unity of invention.

14.08.01 Claims in different categories of invention

In general, it can be presumed when assessing unity of invention a priori that claims in the following categories of invention will satisfy the requirements of section 36 of the Patent Rules when present in a single application:

  • (a) a product and a process for making that product;
  • (b) a product and a use (or method of using) that product;
  • (c) a product, a process for making that product, and a use of that product;
  • (d) an apparatus and a process carried out on that apparatus.

Where the “process for making a product” of (a) or (c) is a “process carried out on an apparatus” within the meaning of (d), claims to the apparatus can be included in a single application with claims to the product, process for making the product and use of the product so long as the product is inventive by reason of properties that arise by virtue of its being prepared using the apparatus.

Note that it is not required that the scope of the claims to subject-matter in different categories of invention be of similar breadth in order to satisfy the requirement of unity of invention. Where the scopes are equivalent, unity will generally exist a priori. Where the scopes are different, unity may still exist.

For example, a broad process for using products could have unity of invention with a narrow product claim defining only a limited number of the products used in that process (see Example 2, below).

Example 1:

An application discloses a fuel burner wherein the use of inlets arranged tangentially to the mixing chamber results in better mixing and more efficient combustion.11

Claims:
  1. A fuel burner comprising tangential fuel inlets into a mixing chamber.
  2. A process for making a fuel burner, comprising the step of forming tangential fuel inlets into a mixing chamber.
  3. A process for making a fuel burner comprising casting step A.
  4. An apparatus for carrying out a process for making a fuel burner, comprising feature X which causes the formation of tangential fuel inlets.
  5. An apparatus for carrying out a process for making a fuel burner comprising a protective housing B.
  6. A process of manufacturing carbon black, comprising the step of tangentially introducing fuel into a mixing chamber of a fuel burner.

Analysis: Unity of invention exists, a priori, among claims 1, 2, 4, and 6. The special technical feature apparently common to these claims is the tangential fuel inlets. Claims 3 and 5 lack this feature, or a corresponding feature [see 14.06], and therefore lack unity of invention both with respect to each other and to the remaining claims. A lack of unity of invention might be identified a posteriori once a search of the prior art had been performed.

Example 2:

An application discloses the discovery that certain compounds, some novel and others known, are useful as plant growth regulants. The compounds are disclosed as a genus (a family of molecules) of common formula A, which comprises specific molecules a1, a2, a3, …, an. Compounds belonging to the sub-genus A' are disclosed as being novel, and a1 is taught as a particularly preferred embodiment. No prior art is cited against the novelty of the compositions of claim 1.

Claims:
  1. A plant growth regulant composition comprising a compound of formula A and a carrier.
  2. A process for regulating plant growth comprising the step of applying a plant growth regulant composition of claim 1 to a plant.
  3. A compound of formula A'.
  4. Compound a1.

Analysis: The claims all define compounds that share a common structure that is responsible for their plant-growth regulant properties. The discovery that this structure results in plant-growth regulant properties (i.e. the allegedly new use of compounds A) appears to be the single general inventive concept linking the claims. There is a priori unity of invention among claims 1 to 4.

14.08.02 Unity without a claim to the inventive linking feature

Since unity of invention is initially assessed a priori in view of the claims and before the prior art is considered, a lack of unity of invention may be identified in a report where the subject-matter of the claims does not appear to share a single general inventive concept.

As noted in 14.05, a single general inventive concept is identified by finding common elements among the various claims. This is generally done by identifying the claim with the fewest elements, and then checking to see if those same elements appear in all the other independent claims. The claims may appear to lack unity of invention a priori where no claim defines solely those elements that are common to all the claims.

An applicant is not required to claim the entire scope of their invention, however, so a claim defining only the common elements is not required in order to provide a linking inventive concept. In performing an a priori assessment of unity of invention, an examiner must consider the teachings of the description and the common general knowledge in the art before concluding that the claims clearly lack a single general inventive concept. If it is clear that the description discloses a particular set of elements that are common to all the claims as being the general inventive concept, unity of invention a priori should be acknowledged.

Where an examiner identifies a lack of unity of invention a priori, an applicant may respond to a report identifying this defect by identifying those features which they consider to be the inventive elements common to all their claims. The examiner may subsequently verify this assertion by performing a search on the basis of those elements.

Example 1:

The application as filed discloses a class of compounds of formula X wherein all members of X are aliphatic organothiophosphates, methods for preparing compounds of formula X and uses of compounds of formula X as insecticides. The description does not suggest that the class of compounds forms part of the invention.

Claims:
  1. A method of preparing a compound of formula X by combining a compound of formula A with a compound of formula B.
  2. The use of a compound of formula X as an insecticide.

Analysis: An a priori assessment of unity of invention presumes the features defined in the claims are those necessary to render the claims novel and inventive. Independent claims 1 and 2 have compounds of formula X in common, but since such compounds have not been claimed it will be presumed (in view of the description) that they are not an invention in and of themselves. The claims therefore appear to lack unity of invention on an a priori basis. Note that no presumption exists that claims to a “method of preparing X” and to a “use of X” share unity of invention [see 14.08.01 for the combinations of claims for which a presumption of unity of invention exists].

If the applicant considers that the class of compounds of formula X are, in fact, novel and inventive, they could respond to a report identifying the apparent lack of unity of invention by asserting that fact. A search of the prior art on the compounds of formula X would validate this assertion. If such a search failed to disclose any relevant prior art, no further searching in respect of the claims would be necessary. If the search identified relevant prior art, the claims would lack unity of invention a posteriori.

Example 2:

The application as filed discloses that a class of known compounds of formula X, wherein all members of X are 3,4-substituted indoles, are 5HT receptor antagonists and are useful as migraine therapeutics and anti-depressants. The usefulness of 5HT receptor antagonists in treating both migraine and depression is known in the art, but the 5HT-antagonist activity of compounds of formula X had not previously been identified.

Claims:
  1. The use of a compound of formula X as a migraine therapeutic.
  2. The use of a compound of formula X as an anti-depressant.

Analysis: The general inventive concept resident in both claims is the discovery that the compounds of formula X are 5HT receptor antagonists. Although this feature is not explicitly defined in each claim, it is understood in view of the description to be the basis of the invention. When read in light of the description, the claims have unity of invention a priori.

14.08.03 Unity of invention and utility

An invention is something that is, inter alia, new, inventive and useful. The utility of claimed subject-matter can be indicative of whether one is dealing with a single invention or multiple inventions.

An applicant must establish the utility of their invention by either demonstration or sound prediction [see section 12.08.03 of this manual]. In cases where utility is being established by sound prediction, the nature of the prediction can inform the unity of invention inquiry. Where the claims include many embodiments, and the utility of all of these could be soundly predicted using a single line of reasoning founded on a single set of facts, it is likely that unity of invention exists among the claims. In contrast, if different parts of the claimed matter would require significantly different sound predictions to support their utility, it is likely that the claims include multiple inventions and that there is a lack of unity of invention.12

Where different embodiments within a given category of invention are claimed (e.g. species within an inventive genus), and the embodiments all share a generic utility, they may be viewed as aspects of a single invention. Where one embodiment has a significantly different utility than the others, it may also be viewed as a different invention.

Consider a drug of generic formula X for treating asthma and a species A within the genus, where A has significantly different utility from a typical drug X. If the substantially different utility exists in addition to the generic utility, the embodiment can be viewed both as an aspect of a single, larger invention and as a separate invention. Such a circumstance arises, for example, in the case of inventions with different levels of preferred embodiments and unity of invention would typically exist in such a case. Consider that species A treats asthma, but without a side-effect common to drug X in general. Species A is an inventive selection from drug X, and could either be claimed in a separate application or in the same application as the genus X.

If the substantially different utility exists in place of the generic utility, however, the one embodiment does not have the same utility as the other embodiments and is, by consequence, a different invention. Unity of invention would typically not exist in such a case. Here, species A turns out to be a very good decongestant but is not useful in treating asthma. It does not share unity of invention with the genus X.13

14.08.04 Markush groups and lists of alternatives

A Markush group must define a list of alternatives that, for the purposes of the claimed invention, can be viewed as technical equivalents that perform the same function in substantially the same way. The person skilled in the art should expect that one member of a Markush group is directly substitutable for another in operable embodiments of the invention. A Markush group is identified by the form “an [alternative] selected from the group consisting of [a1, a2, a3, an-1], and [an]”.

Markush groups are most common in the chemical arts; a group of chemical compounds may be appropriately defined in a Markush group if each alternative has a common property or activity and either

  • (a) shares a common structure with all other alternatives, wherein the shared structure is relevant to the activity of the alternatives in the invention; or
  • (b) belongs to a class of compounds recognised in the art to which the invention pertains and all members of the group would be expected to behave the same way in the context of the invention.

Where the alternatives defined in a Markush group do not satisfy the requirements of (b), and where unity of invention cannot be established by elements in the claim other than the Markush group, either the shared structure referred to in (a) or its utility in the context of the invention would need to be novel and inventive over the prior art in order to provide unity of invention to the claimed alternatives.

Where a list of alternatives satisfies the requirements set out above, unity of invention will generally be acknowledged whether the alternatives are claimed in the form of a Markush group or not.14

14.08.05 Intermediates and final products

An intermediate that is physically or chemically transformed to produce a final product may be considered to have unity of invention with the final product, despite that the inventive step and utility that support the patentability of the intermediate and final product may be quite distinct from each other.

The intermediate must, necessarily, be useful for producing the final product. It may also have the same utility as the final product, although this is not required.

To have unity of invention with the final product, the intermediate should share with the final product the principal structural elements of the final product or should serve to introduce to the final product a structural element that is essential to its utility. Different intermediates that introduce different structural parts to the final product, however, will generally not be considered to share unity of invention amongst each other.15

Furthermore, the intermediate must be a direct precursor to the final product, in the sense of being removed from the final product by only one or a few steps, and must not be a precursor to a subsequent intermediate that is known in the art and that must be produced on the way to the final product.16

The concept of “intermediates and final products” is common in chemical synthesis, but could apply in other arts as well.

Chemical examples of intermediates and final products that could be considered to have unity of invention include:

  • (i) a biologically inactive compound (the intermediate) that is deprotected to produce an active drug (the final product). The deprotection renders the final product active, but the overall structure of the intermediate and the final product are otherwise almost equivalent;
  • (ii) an intermediate in a multi-step synthesis that contains a structure which, upon ring-closing, produces a critical functionality in a final product, where the final product is prepared by reacting the intermediate with a polycyclic aromatic compound and subsequently ring-closing the structure introduced by the intermediate. The intermediate and the final product have very different structures, since the intermediate does not include the polycyclic scaffold of the final product. Nevertheless, the critical element of the final product results directly from the intermediate, and there are no known intermediates produced in the synthetic steps leading from the claimed intermediate to the final product.
Example 1:

An application discloses an industrially useful triazole compound defined by formula I, and a method for its preparation by ring-closure of a compound of formula II. The critical structure in the triazole product is the combination of the triazole ring (sub-structure A) with proximal substituted aromatic rings (structures B and D). The necessary stereochemistry of the groups A, B and D is provided by a central ring structure C. The description teaches that the ring structure C can be formed by a ring-closing reaction of functional groups E and F, which are present in the immediate precursor to the final product. The only disclosed utility of the intermediate is in the production of the final product.

Claims:
  1. A compound of formula I comprising sub-structures A-B-C-D.
  2. A compound of formula II comprising sub-structures A-B-E-F-D.

Analysis: Although the core structures of compound I (final product) and compound II (intermediate) differ considerably, compound II is an open-ring precursor to compound I. Both compounds share principal structural elements, namely the triazole A and the substituted aromatic rings B and D. The intermediate structure E-F is, from a chemical perspective, a known precursor for rings of type C. The two structures are, overall, technically closely interrelated and unity of invention exists.17

Example 2:

An application discloses two structurally related molecules A and B. Molecule A is a compound with analgesic properties. Molecule B results from selective methylation and acylation of two hydroxy groups on A. Compound B is not an effective analgesic, but has significant bioactivity as a sedative.

Claims:
  1. A compound of structure A.
  2. A compound of structure B.
  3. A method for converting compound A into compound B through sequential selective methylation and acylation, comprising the steps […].
  4. A use of A as an analgesic.
  5. A use of B as a sedative.

Analysis: Compound A is an intermediate that is structurally similar to compound B. Claims 1 and 2 share unity of invention, and share unity of invention with claim 3.

Claim 5 defines the use of compound B, and shares unity of invention with claims 2 and 3 (a product, process to produce the product and use of the product - see 14.08.01). Although claim 5 does not clearly share unity of invention with claim 1, claims 1, 2, 3 and 5 would typically be considered to have unity of invention in a single application (intermediate to produce B, compound B, process to produce B, and use of B).

Claim 4 lacks unity of invention with claims 2, 3 and 5 as it defines a use of intermediate A other than its use in preparing the final product or an equivalent use to the product's. Claim 4 (use of A) does share unity of invention with claim 1 (intermediate A). If desired, claim 3 could be included in an application with claims 1 and 4 (considering claim 3 to be a use of A), although in practice it would usually be preferable to include claim 3 in the same application as claims 2 and 5 (considering claim 3 to be a process to produce B).18 Claim 4 could be claimed in a divisional application.

14.08.06 Multi-step methods of preparation

Some preparative methods will include more than one step that could be patentable independently of the multi-step preparative method as a whole. This applies particularly to multi-step synthetic methods, although in principle the concepts could apply to any multi-step preparative method (e.g. a method of manufacturing).

For the purposes of unity of invention, an application can include a claim to a single inventive transformative step in a method and to any larger method involving that step up to the entire multi-step method. The utility of the transformative step arises from it transforming a precursor (which will be a starting material or intermediate in the overall method) into a product (which may be a further intermediate in the method or its final product). The transformative step will also typically share unity of invention with its product, and may share unity of invention with certain of the product's precursors (see 14.08.05).

Other individual steps in the method (or combinations of steps that do not include the inventive transformative step), however, will not have unity of invention with the inventive transformative step. The other step or combinations of steps do not share the general inventive concept of transforming the inventive transformative step's precursor into its product. Products other than those meeting the “intermediate and final product” requirements set out in 14.08.05 will likewise be considered not to share unity of invention with the inventive transformative step and its product.

Consider a multi-step synthesis involving the following steps:

  • step A transforming 1 into 2;
  • step B transforming 2 into 3;
  • step C transforming 3 into 4;
  • step D transforming 4 into 5; and
  • step E transforming 5 into 6.

The applicant considers steps A and D to be inventive, as well as the 5-step method as a whole. Starting material 1 and intermediates 3 and 4 are known, while intermediates 2 and 5 and final product 6 are novel.

The application includes claims to step D, to step E, and to intermediate 5 and the closely structurally-related final product 6. Unity of invention can be acknowledged among these claims as involving inventive product 5, a method for producing product 5 (step D), a method of using product 5 (step E) and by virtue of the “intermediate / final product” relationship between products 5 and 6 [see 14.08.05]. Unity of invention could not be acknowledged between intermediate 5 and intermediate 2 because of the intervening known intermediates 3 and 4 [see 14.08.05], nor could individual steps A, B or C be claimed either alone or in any combination other than one ending with step D (i.e. so that the combination could be viewed as a method for producing 5).

It is worth noting that other groups of claims could be identified which would meet the requirement for unity of invention. For example, a claim to the 5-step method as a whole would have unity with a claim to product 6, to intermediate 5 and to any combination of steps that includes step E on the basis of the general inventive concept being “the preparation of 6 from 5”.

14.08.07 Unity and provisos

A proviso is a clause added to a claim in order to remove something that would otherwise be encompassed by the language of the claim.

A proviso may be used, for example, to provide or restore novelty in cases where some part of the claimed subject-matter would otherwise be anticipated.

Whether a proviso causes a lack of unity of invention must be assessed on the facts of a given case. A proviso can be thought of as making the subject-matter of the claim “discontinuous”, and in that sense can remove the generality of what would otherwise be a “general inventive concept”.

In assessing whether a proviso will have the effect of removing unity of invention from the claimed subject-matter, the reason for including the proviso must be considered. Where a proviso is used to avoid prior art, for example, the critical question is whether the prior art has simply disclosed an embodiment falling within a claim or has taught the same inventive concept as the application. In the latter case, unity of invention is most likely absent in view of the proviso whereas in the former this may not be the case.

Example:

An application discloses a genus of compounds (compounds comprising the structure of formula I) useful as antibiotics. The inventors have discovered and disclosed a structure-function relationship based on a certain functional group in the genus. The same applicants had, several years earlier, obtained a patent on a species (species A) falling within the genus. At the time the previous patent was obtained, the applicants knew the species was a useful antibiotic but did not know what structure led to the activity.

Claims:
  1. A compound comprising the structure defined by formula I, provided that said compound is not “species A”.
  2. A compound according to claim 1, wherein said compound is species B.
  3. A compound according to claim 1, wherein said compound is species C.
  4. A compound according to claim 1, wherein said compound is species D.

Analysis: The general inventive concept linking the compounds of formula I is the presence of the functional group responsible for their antibiotic activity, coupled with the discovery of the structure-function relationship. The prior patent had not disclosed the structure-function relationship, and although species A would anticipate the broad genus claim in the absence of the proviso, the proviso does not result in a lack of unity of invention among the remaining members of the genus.

Note that if the earlier patent had identified the structure-function relationship in respect of species A, it would imply a lack of unity of invention a posteriori since the role of the functional group in providing antibiotic activity would have been known.

14.08.08 Additional examples

As noted in 14.04, the Canadian standard for unity of invention is equivalent to that under the Patent Cooperation Treaty.

Additional examples helpful for understanding unity of invention can be found in sections 10.20 to 10.59 of the PCT International Search and Preliminary Examination Guidelines, available on the web site of the World Intellectual Property Organization.19

14.09 Right to file a divisional application

In accordance with subsections 36(2) and 36(2.1) of the Patent Act, where an application (the “original application”) describes more than one invention, an applicant may file a divisional application to protect described inventions other than the one invention only to which the original application's claims were directed or, as the case may be, to which the original application's claims were limited.

In accordance with subsections 36(2), 36(2.1) and 36(3) of the Patent Act, a divisional application must be filed before the original application either grants to patent or, where the original application has been abandoned, the period to reinstate it expires.

Only an applicant may file a divisional application, and only within the time period provided by statute. Although the term “applicant” is defined in section 2 of the Patent Act as including “an inventor and the legal representatives of an applicant or inventor”, the Office takes the position that only the current owner of the application can divide it by filing a divisional application.

14.10 Filing requirements for a divisional application

The filing of a divisional application is largely equivalent to the filing of an original application [see Chapter 5 of this manual].

When preparing the Petition (Form 3 of Schedule I of the Patent Rules), section 2 is completed. The Office considers any assignment registered in respect of the original application to also be registered in respect of the divisional application. In addition, any priority requested in respect of the original application will be considered to have been requested in respect of the divisional application unless the applicant advises the Office in writing that one or more priority claims are not to be considered.20

In accordance with subsection 36(4) of the Patent Act21, a divisional application is considered to be filed on the same date as the original application. In accordance with subsection 99(2) of the Patent Rules, any maintenance fee set out in item 30 of Schedule II of the Patent Rules that would have been payable pursuant to subsection 27.1(1) of the Patent Act had the divisional application been filed on the filing date of the original application shall be paid when the divisional application is actually filed.

In accordance with subsection 96(2) of the Patent Rules, a request for examination of a divisional application shall be made and the fee shall be paid before the later of the five-year period after the filing date of the original application and the six-month period after the date on which the divisional application is actually filed.

The Office takes the position that the applicable fee for requesting examination of a divisional application is that set out in item 3(b) of Schedule II. This is so irrespective of whether or not the original application resulted from the national phase entry of an international application that was the subject of an international search by the Commissioner.22

14.11 Meaning of “original application”

In accordance with subsection 36(4) of the Patent Act, a divisional application shall be deemed to be a separate and distinct application under the Act, to which the Act's provisions apply as fully as may be.

The Office takes the position that a divisional application may itself be considered an original application under section 36 of the Patent Act for the purposes of the filing of further divisional applications.

Thus, if a first application (the “grandparent” application) leads to a first divisional application (the “parent” application), a further divisional application (the “child” application) may be filed on the basis of either the parent application or the grandparent application.

The Office takes the position that in order for a divisional to be filed, section 36 of the Patent Act requires that either the parent or grandparent be eligible as an “original application”, but not both. If, for example, the grandparent issued to patent or became abandoned and the period to reinstate expired, the parent application could be used to file a divisional in accordance with subsections 36(2), 36(2.1) and 36(3) of the Patent Act. This allows the provisions of these subsections to apply “as fully as may be” to the parent application, as provided for in subsection 36(4) of the Patent Act.

14.12 Time limits

In accordance with subsection 36(4) of the Patent Act, a divisional application shall have the same filing date as the original application.

Unless otherwise provided for in the Act or Rules, any time limit that would apply to a regularly filed application applies to a divisional application.

Where a divisional application is filed after the expiry of the 18 month confidentiality period specified in section 10 of the Patent Act, the application and any documents filed in connection with it shall be open to public inspection immediately upon filing. Note that the confidentiality period of a divisional application is calculated based on the earliest filing date of any previously filed application on which a request for priority is made in respect of the divisional application. A divisional application may not have all the priority claim dates that the original application from which it was divided has.

14.13 Examination of divisional applications

Where a request for examination has been made on a divisional application, examination will include a determination of whether the application is entitled to divisional status. The content of the specification and drawings of the purported divisional application are compared to that of the original application to determine if the claims of the divisional application are directed to a different invention than the claims of the parent, and if the divisional application contains any subject-matter that would have contravened subsection 38.2(2) or 38.2(3) of the Patent Act had it been added to the original application's specification or drawings by way of amendment.

Subsections 38.2(2) and 38.2(3) of the Patent Act provide that the specification and drawings, respectively, may not be amended to describe matter not reasonably to be inferred from the specification or drawings as originally filed (“new matter”). If the specification or drawings of a purported divisional application contain new matter with respect to the specification or drawings of the original application, the later filed application is not entirely based on the specification and drawings of the original application and is not entitled to divisional status. Simply put, something cannot be divided out of an application that could not legitimately have formed part of that application.

Similarly, if the claims in the purported divisional application are not directed to a different invention than those of the original application, the later-filed application is not a divisional application within the meaning of section 36 of the Patent Act.

A divisional application will be examined in its regular order according to the date on which the parent application's request for examination was made.

If, during examination, the later-filed application is considered to be not entitled to divisional status, the applicant will be notified of this conclusion and of the examiner's reasons for so concluding. Examination will proceed on the presumption that the application's filing date is the date on which the documents were actually submitted to the Office. Note that for practical reasons23, the electronic records of the Office will not be updated in view of this presumption unless the applicant subsequently agrees that the application is not a divisional application. An applicant may also respond to a requisition identifying the application as not entitled to divisional status by amending the application so that it becomes entitled to divisional status, or by providing arguments sufficient to convince the examiner that it is already entitled to that status.

Although the filing of an improper divisional is not, of itself, a defect in the application,24 statements in the description asserting that the application is a divisional application will be considered inaccurate and be identified as defects under subsection 27(3) of the Patent Act.

Depending on the facts of the case, the purported “original application” may also be relevant prior art against the later application in the evaluation of novelty, obviousness or double-patenting. Note that if the filing of a divisional application was “directed by the Patent Office”, the doctrine of double-patenting does not apply between the divisional and any of its parent or sibling applications.25


Endnotes

1Consolboard Inc. v. Macmillan Bloedel (Saskatchewan) Ltd. [(1981), 56 C.P.R. (2nd), 145 (S.C.C.)] at page 168 referring to “the well-known rule that only one patent may issue for a given invention”; and Teva Canada Ltd. v. Pfizer Canada Inc. 2012 S.C.C. 60 at paragraph 58 affirming that “a patent shall be granted for one invention only.”

2Or of a divisional application to cover several additional inventions disclosed in the parent application, or of one or several divisional applications each to cover one of several additional inventions disclosed in the parent application.

3Merck & Co., Inc. v. Apotex Inc. 2006 FC 524 at paragraph 203. Hughes J. also noted at paragraph 197 that “[d]uring the pendency of an application or several applications, the procedures to be followed are the prerogative of the Patent Office”.

4Libby-Owens-Ford Glass Co. v. Ford Motor Co. [(1970), 62 C.P.R. (1st), 223 (S.C.C.)] at pages 230-231, Ciba-Geigy AG v. Commissioner of Patents [(1982), 65 C.P.R. (2nd), 73 (F.C.A.)] at page 79

5Sociéte des Usines Chimiques Rhone-Poulenc et al. v. Jules R. Gilbert Ltd.  [1966] Ex. C.R. 59 at paragraphs 6-8

6In view of this, some content in this chapter mirrors or has been adapted from text found in the PCT International Search and Preliminary Examination Guidelines published by the World Intellectual Property Office (Geneva, 2011).

7Article 27(1) PCT states: No national law shall require compliance with requirements relating to the form or contents of the international application different from or additional to those which are provided for in this Treaty and the Regulations.

8Teva (supra at 1) at paragraph 64

9For an example of corresponding elements, see section 10.29 of the PCT International Search and Preliminary Examination Guidelines (supra at 6).

10This example is adapted from the example provided in section 10.23 of the PCT International Search and Preliminary Examination Guidelines (supra at 6).

11This example is adapted from the example provided in section 10.26 of the PCT International Search and Preliminary Examination Guidelines (supra at 6).

12The conclusion reached in section 10.43 of the PCT International Search and Preliminary Examination Guidelines (supra at 6) can be understood in this light, presuming that a single line of reasoning cannot soundly predict why the various classes of herbicide B work with A to achieve the inventive result.

13See also the PCT International Search and Preliminary Examination Guidelines (supra at 6) at 10.42.

14The conclusion reached in section 10.58 of the PCT International Search and Preliminary Examination Guidelines (supra at 6) can be understood in this light, since compounds X, Y and Z do not share a structural feature responsible for their activity. It must be presumed that X, Y and Z are not members of a recognised class of compounds.

15Due regard should be given to the nature of the synthesis in performing this evaluation. The relationship of the structure of an intermediate to the final product will be quite different in, for example, a convergent synthesis than in a divergent synthesis, or in a ring-closing or rearrangement reaction than in an addition reaction. See also the PCT International Search and Preliminary Examination Guidelines (supra at 6) at 10.18(f).

16See the PCT International Search and Preliminary Examination Guidelines (supra at 6) at 10.18(e).

17This example is loosely based on the PCT International Search and Preliminary Examination Guidelines (supra at 6) at 10.47, which provides specific chemical structures to illustrate the same point.

18A method for preparing a product would usually be considered to render the product it produces obvious, and there could consequently be an appearance of double-patenting if claims 2 and 3 appeared in different applications.

19PCT International Search and Preliminary Examination Guidelines (supra at 6).

20Note that where the applicant has made a request in section 4 of the Petition for fewer priority documents than requested for the original application, only those priority claims requested in section 4 will be considered to have been made in respect of the divisional application.

21An equivalent provision exists for applications filed prior to October 1, 1989, under subsection 36(4) of the Patent Act as it read immediately before that date.

22This interpretation is consistent with the provisions of subsection 36(4) of the Patent Act and of subsection 58(10) of the Patent Rules (which provides that an international application can only become one national phase application).

23Many time periods are calculated from the assigned filing date. Prematurely changing the electronic records of the Office may result in confusion and potential risks to the applicant.

24Merck (supra at 3) at paragraph 203

25Consolboard (supra at 1) at page 169



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