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The Duty of Good Faith in Patent Prosecution:
Where Will It Arise Next?
By Barbara Murchie and Christopher Heer, Bennett Jones LLP1 Under the Patent Act, an applicant for a Canadian patent has two statutory obligations to act in good faith. Section 53 requires the applicant to be honest and complete in the description of the invention in the specification; section 73 requires the applicant to respond in good faith to the The Federal Court has also suggested there may be a more general duty to act in good faith beyond that specifically set out in the Patent Act. This general duty can be framed in terms of the bargain theory. In return for full, frank and fair disclosure of its invention, an applicant will be granted a twenty year monopoly to that invention. If the applicant's disclosure and/or dealings with the Patent Office are misleading, then the patent has been granted on a false premise and/or the applicant's bargain with the public has not been honoured. Those arguing against a more general duty will note that the Patent Act specifically sets out and limits the good faith obligations to the circumstances described in the legislation. In the context of discussing the requirements for the patent specification, Dr. Fox explains that because a patent represents a bargain between the inventor and the public with some consideration flowing in both directions, "the utmost good faith must be observed by the applicant in disclosing his invention and in framing his specification, which must not contain any false representation or be willfully misdescriptive or misleading in any material part"2. Section 1 Barbara Murchie is a partner in the intellectual property litigation group of the Toronto office of Bennett Jones LLP, practicing primarily in the area of pharmaceutical patent litigation. Christopher Heer is an associate lawyer and registered patent agent in the intellectual property litigation group of the Toronto office of Bennett Jones LLP, practicing primarily in the area of patent litigation. 2 Harold G. Fox, The Canadian Law and Practice Relating to Letters Patent for Inventions, 4th ed. (Toronto: Carswell, 1969) at 178. 53 has codified this good faith requirement and provides a penalty for failing to honour it; if any material allegation in the specification is found to be intentionally misleading, the patent is void. In a more general statement, Dr. Fox goes on to say that good faith is "a necessary incident. The inventor must act uberrima fide and and there must be no false suggestion".3 Under section 35 of the Patent Act, every patent application filed with the Canadian Patent Office must be examined by a competent examiner for compliance with the Patent Act and Patent Rules. During this examination, the patent applicant is given the opportunity to address areas of alleged non-compliance by responding to requisitions from the examiner to which the applicant may either amend its application so that it does comply or make arguments as to why the application already complies. Pursuant to section 73(1)(a) of the Patent Act, these responses by the applicant must be made in good faith, failing which the patent application goes There are two Canadian court decisions (Lundbeck v. Ratiopharm, 2009 FC 1102 and G.D. Searle v. Novopharm Limited, 2007 FC 81) that find a breach of the duty of good faith under section 73(1)(a) of the Patent Act in the PMNOC context. This paper reviews those decisions and sections of the Patent Act and Patent Rules to comment on the extent of the duty of good faith under section 73(1)(a) in Canada. We then examine other decisions which have found or rejected a more general duty of good faith in dealing with the Patent Office in Canada. Next, we provide a summary of the U.S. inequitable conduct doctrine and the statutory differences which make reference to U.S. inequitable conduct jurisprudence in Canada problematic. Finally, the article concludes with suggested best practices relating to the duty of good faith for both patent prosecutors and patent litigators.

1. The Duty of Good Faith in Patent Prosecution in Canada
A. The Duty of Good Faith in the Patent Act and Patent Rules
The duty of good faith in patent prosecution in Canada arises by statute in section 73(1)(a) of the post-1996 Patent Act. Section 73(1)(a) prescribes "[a]n application for a patent in Canada shall be deemed to be abandoned if the applicant does not reply in good faith to any requisition made by an examiner in connection with an examination, within six months after the requisition is made or within any shorter period established by the Commissioner." The language of the section defines both who owes the duty of good faith and under what Who Owes a Duty of Good Faith in Patent Prosecution?
The duty of good faith according to section 73(1)(a) is owed by the applicant. Unlike in the United States, the applicant's patent agent (or associate patent agent) in Canada does not owe a duty of good faith independent of that of the applicant. While Rule 22 of the Patent Rules provides "any act by or in relation to a patent agent or an associate patent agent shall have the effect of an act by or in relation to the applicant", there is no court decision that extends the s. 73 duty of good faith to the patent agent to disclose anything known to him that does not relate to the activities of the applicant. Since the duty of good faith is owed by the applicant, the applicant's knowledge may be presumed to include, for example, prior art references cited in prosecution of related and corresponding foreign patent applications. This imputed knowledge can be considerable in cases where the applicant has, for instance, submitted a long list of prior art in an information disclosure statement before the U.S. Patent Office in a corresponding U.S. application. Under What Circumstances Is the Duty of Good Faith Owed?
The duty of good faith under section 73(1)(a) of the Patent Act is owed in replying to any requisition made by an examiner in connection with an examination. Consequently, not every communication with the Patent Office is subject to the duty of good faith under section of Requisitions may be made under the following sections of the Patent Rules:  Rule 23 – appointment of patent agents  Rule 29(1) – corresponding examination information and related documents  Rule 29(2) – identification of first publication  Rule 30(2) – non-compliance with Act or Rules - amend or argue against defects  Rule 30(4) – final action for non-compliance with Act or Rules - amend or argue against  Rule 30(5) – payment of final fee after final action rejection withdrawn  Rule 58(4) – translations of international applications  Rule 58(5) – evidence that applicant is the legal representative  Rule 71 – translations of documents  Rule 89 – certified copies of priority documents  Rule 94 – application completion requirements  Rule 104.1 – date of deposit of biological material  Rule 136 (sandwich Patent Act) – translations of documents  Rule 143 (sandwich Patent Act) – certified copies of priority documents  Rule 172 (old Patent Act) – translations of documents  Rule 180 (old Patent Act) – certified copies of priority documents When is the Duty of Good Faith Breached?
The duty of good faith is breached by a lack of good faith, and therefore does not require proof of bad faith or fraud by the applicant (although such evidence would demonstrate a lack of good faith). Since this intent threshold is lower than fraud or bad faith, the Court has considered the materiality of the alleged breach to the examination of the application in view of the fact that finding a breach of the duty of good faith will almost always invalidate a patent in a litigation Examples of where a lack of good faith has been found are provided in the two cases below. B. Breach of the Duty of Good Faith Under s. 73(1)(a) in Canadian Case Law
1) G.D. Searle v. Novopharm Limited
In G. D. Searle v. Novopharm Limited, 2007 FC 81, Novopharm alleged that Searle misled the Canadian Patent Office in two respects during the course of the prosecution of the application for the „576 patent at issue. The first was to say that the European Patent Office had allowed claims identical to claims 1 to 16 to proceed to a patent, whereas in fact the European Patent Office had done so in respect of only claims 1 to 8. The second was to not disclose certain information relating to the Matsuo reference, which appeared at page 2 of the patent and later in responses to In respect of the first alleged breach of the duty of good faith, Justice Hughes noted that while claims 1-8 included the subject matter of claims 4 and 8 in Canada, the other claims 9-16 did not relate to any claims in the Canadian patent. He also noted that a subsequent response provided the information that only claims 1-8 had been allowed, even though the information was not specifically referred to or highlighted. Justice Hughes found nothing on the record to indicate that the incorrect statement materially influenced the examiner, nor was there any information as to the intent of the applicant or its patent agent. He therefore concluded that there was no basis for finding abandonment of the application for lack of good faith as the materiality of the misrepresentation was low and evidence of intent was lacking. In respect of the second alleged breach of the duty of good faith, Searle had tested at least one of the compounds in the prior art Matsuo reference and found that it was useful in treating inflammation without causing gastric problems. Searle disclosed that finding to the public before the Canadian Patent application was filed. But before the Patent Office, Searle had said only that the Matsuo reference, on its face, does not state that at least one of the compounds described in that reference did not cause gastric problems while being effective as against inflammation. In his decision, Justice Hughes wrote that all appropriate facts relating to the prior disclosure should have been stated in the patent application itself and disclosed to the Patent Office so as to allow the examiner to make an appropriate assessment respecting the specification and proposed claims. He found that, without fuller disclosure about Matsuo, good faith was not shown in submitting the application to the Canadian Patent Office. Further, good faith was not shown subsequently in responses to the Patent Office examiner dealing with Matsuo. As a result, he concluded that the application had been abandoned under section 73(1)(a) of the Patent Act. In the course of his decision, Justice Hughes also remarked that "an application for a patent is effectively an ex parte proceeding, only the applicant and the Patent Office examiner are involved in dialogue".4 In ex parte proceedings, the party submitting the evidence in support of the requested relief must fairly and fully disclose all material facts relating to the requested relief or face a later lifting of the order granted. This analogy was later picked up by Justice Mactavish On appeal, Justice Hughes' order was reversed without comment on the issue of lack of good faith on the basis that Searle was the applicant on the claim date, and therefore the prior disclosure fell within the applicant's one-year grace period.5 2) Lundbeck Canada v. Ratiopharm
In Lundbeck Canada v. Ratiopharm, 2009 FC 1102, two patents were at issue. Lack of good faith was alleged against only one of the patents, the '492 patent. The '492 patent was also alleged to be invalid for lack of utility and invalid as anticipated and obvious in view of two references: the Justice Mactavish did not find the allegations of anticipation or obviousness justified. However, she did find that the allegation that the '492 patent was invalid for lack of utility was justified. In respect of the duty of good faith, ratiopharm asserted that the applicant failed to make full, frank and fair disclosure of the import of the Wenk article. In particular, ratiopharm alleged that in responding to a requisition from the examiner, the applicant misrepresented that the prior art "taught away" from using a combination of memantine and an acetylcholinesterase inhibitor in 4 G. D. Searle v. Novopharm Limited, 2007 FC 81 at para. 72. 5 G. D. Searle v. Novopharm Limited, 2007 FCA 173 the treatment of Alzheimer's disease and that this constituted a failure to communicate with the In the prosecution of the application leading to the '492 patent, the examiner had noted that the claims were directed to an aggregation of two known types of compounds and remarked that there was no invention in combining two known compounds unless there was a new use or unless the combination of the two compounds to perform the old use provided "a new and unexpected result". The examiner further commented that there was no evidence that a synergistic effect occurs between the two compounds in the treatment of mild cognitive impairment or dementia. In addition, the examiner made a requisition, pursuant to Rule 29 of the Patent Rules, that the applicant identify any prior art cited in respect of the United States and In response to the Rule 29 requisition, the applicant responded that there were no corresponding United States or European Patent Office applications pending. The applicant then went further and indentified two documents cited in the International Search Report, one of which was the Wenk article. The response did not discuss the Wenk article or provide a copy of the article to the examiner, nor was either action required. Subsequent to the applicant's identification of Wenk, a requisition was sent by the examiner which reiterated the obviousness rejection. The examiner stated that "the applicant has failed to show that their combination results in a unitary result, and not a mere addition of the effects of the two known drugs". It was the applicant's response to this rejection that ratiopharm took issue with. The applicant's response included the following statement: … In order to evaluate the inventiveness of the present invention, it is important to appreciate the understanding a person skilled in the art would have had at the time of filing of the present application. It is therefore of prime importance to note that, at that time, there were numerous articles in the prior art which warned against the combination of NMDA antagonists and AchE [or acetylcholinesterase] inhibitors because NMDA antagonists attenuated the effect of AchE inhibitors, i.e. NMDA antagonists rendered AchE inhibitors ineffective… The applicant then went on to discuss four such articles and concluded as follows: [I]t would thus have been counter-intuitive and definitely improbable that, in view of the prior art available at the time of filing, one skilled in the art would have been prompted to combine a NMDA antagonist with an AchE inhibitor to achieve the claimed composition. In fact, in view of the prior art, which showed that NMDA antagonists attenuate the effect of AchE, it was not obvious for a skilled person to arrive at the present invention. Indeed, the prior art clearly teaches away from the combination of a NMDA antagonist with an AchE inhibitor as claimed in the instant application. It is therefore the Applicant's opinion that the teachings of the prior art as a whole would not have prompted the skilled person faced with the problem of formulating a composition for the treatment of mild cognitive impairment or dementia, to elaborate the instant composition and that consequently the claims on file are not obvious in view of the prior art. Therefore, withdrawal of this objection is respectfully requested. [emphasis added] Ratiopharm argued that in this response the applicant breached its duty of good faith in failing to alert the examiner to the importance of the Wenk article, which taught that while some acetylcholinesterase inhibitors do lose their therapeutic effect when used in conjunction with memantine, others do not. In particular, Wenk found that memantine's inhibitory effect was restricted to "irreversible" acetlycholinesterase inhibitors such as DFP, and that other "reversible" acetylcholinesterase inhibitors such as donepezil, THA (or tacrine hydrochloride) and galantamine did not lose their therapeutic effect when used in conjunction with memantine. In her review of the duty of good faith, Justice Mactavish found that paragraph 73(1)(a) of the Patent Act explicitly imposes a duty on patent applicants to "reply in good faith to any requisition made by an examiner in connection with an examination" and that the only cases considering the scope of paragraph 73(1)(a) are the Federal Court decision in G.D. Searle v. Novopharm (discussed above) and the decision of the Federal Court of Appeal reversing it. After discussing the G.D. Searle decisions, Justice Mactavish remarked that it is noteworthy that the Federal Court of Appeal did not take issue with Justice Hughes' review of the law with respect to the duty of good faith in the prosecution of patent applications. From this, she accepted Justice Hughes' review as an accurate overview of the obligations on an applicant and expressly agreed with the analogy drawn between an application for a patent and an ex parte court proceeding.6 Justice Mactavish found that the examiner was concerned about the fact that the use of both memantine and acetylcholinesterase inhibitors was already known in the prior art for the 6 The analogy to an ex parte proceeding appears to relate to the general duty of good faith in patent prosecution. There is no statutory requirement to disclose information material to patentability, as there is in the United States. treatment of mild cognitive impairment or dementia. She further found the applicant had in response discussed four articles referencing acetylcholinesterase inhibitors which were not referenced in the patent whereas the one study that was relevant to the combination of the acetylcholinesterase inhibitors discussed in the patent and memantine was Wenk, which was not discussed. In other words, the applicant provided the examiner with four less relevant items of prior art which "taught away" from pursuing the invention, yet failed to mention the one directly relevant study that came to the opposite conclusion. In view of those findings, Justice Mactavish concluded that it was not a fair representation of the prior art to say "the prior art clearly teaches away" from combining an NMDA antagonist with an acetylcholinesterase inhibitor while also saying the four less relevant studies were "of prime importance" to the issue of obviousness. She remarked that surely Wenk was even more important given that it was far more relevant than any of the four studies cited in the response. Justice Mactavish therefore found ratiopharm's allegation of abandonment based on a breach of the duty of faith justified. She further commented that "[a] proper understanding of the prior art is clearly critical to patent examination. The duty of good faith imposed by paragraph 73(1)(a) of the post-1996 Patent Act requires that this prior art be fully and fairly described by applicants and their agents when answering requisitions from the Patent Office." In considering Justice Mactavish's reasons as a whole, it is unclear whether anything in her analysis turns on the applicant having identified the Wenk reference in response to the Rule 29 requisition. If Wenk had not been voluntarily identified to the Canadian examiner, Wenk still have been known to the applicant and the applicant's response could still be said to lack good faith. But, on the other hand, the identification of the Wenk reference to the examiner may have made it easier for the Court to infer the applicant lacked a good faith intent in omitting discussion of Wenk from its response, as opposed to doing so by inadvertence or mistake. Is There a Duty of Good Faith Outside of the Circumstances of Sections 53 and 73?
Whether there is a more general duty of good faith in applying for a patent is unsettled. On the one hand, expecting an applicant for a twenty year monopoly to act in good faith in dealing with the Patent Office and in describing his or her invention does not seem oppressive. One might question the need to codify such a requirement at all; surely it goes without saying that the description of the invention and the dealings with the patent examiner must be honest and complete as both form the basis on which the monopoly is granted. On the other, an undefined good faith obligation may be onerous for the court to enforce and create uncertainty in patent applicants as to their obligations. In a similar context, however, the common law courts have had no difficulty articulating and applying the tests for negligent and fraudulent misrepresentation in a contractual context without debilitating uncertainty in the public and business community. Although the Federal Courts are not common law courts with inherent jurisdiction, they are courts of equity with the tools required to interpret and apply legislation within their jurisdiction. Interpreting the Patent Act, for instance, to allow an applicant to lie to an examiner in a representation that falls within neither s. 53 nor s. 73 cannot be justified. Court decisions addressing whether there is a general duty of good faith outside of the circumstances of sections 53 and 73 of the Patent Act are summarized below. In Pason Systems v. Commissioner of Patents, 2006 FC 753, a correction of a clerical error made pursuant to section 8 of the Patent Act was set aside on the basis that the ongoing litigation concerning the claim was not disclosed to the Patent Office. In his reasons, Justice Hughes wrote that "the applicant and its agent owe a duty of candour to the Patent Office to make a full, fair and frank disclosure of all of the relevant circumstances." Justice Hughes' authority in support of this statement was the Code of Ethics of the Intellectual Property Institute of Canada which In G. D. Searle v. Novopharm Limited, 2007 FC 81 (discussed above), Justice Hughes called upon a more general duty of good faith to find the patent invalid due to the applicant's failure to disclose, in the patent application, its earlier publication of test results showing that a structurally similar compound had the same properties as the compound claimed in the patent. Justice Hughes found that a misleading or one-sided description of prior art in a patent application could breach a more general duty of good faith in dealing with the Patent Office. Justice Mactavish in Lundbeck v. Ratiopharm, 2009 FC 1102 (discussed above) quoted G.D. Searle for the points that (1) a patent application is like an ex parte proceeding, (2) that dealings with the Patent Office must be in good faith, and (3) that the specification, being the disclosure for which the monopoly is granted, should be full, frank and fair. Although her decision was based on lack of good faith in a response to a requisition made by an examiner in connection with an examination, which therefore invoked the duty of good faith under section 73(1)(a) of the Patent Act, Justice Mactavish appears to accept a more general duty of good faith. In Hershkovitz v. Tyco Safety Products Canada Ltd., 2009 FC 256, Justice Martineau found the disclaimers at issue to be invalid, writing that "[t]he patentee must be able to demonstrate to the Court that the disclaimer is made in good faith and not for an improper purpose. Where the patentee does not discharge this burden, the disclaimer will be held to be invalid. The fact that the Patent Office had accepted a disclaimer is not determinative." Moreover, referencing the G.D. Searle decision of Justice Hughes, Justice Martineau commented more generally as An obligation arises on those seeking to gain a patent to act in good faith when dealing with the Patent Office as there is ample opportunity afforded during the prosecution to make further disclosure. Therefore, while there is no statutory deadline for filing a disclaimer, the public disclosure function of patents and the general duty of good faith nevertheless require that a patentee file a disclaimer against an issued patent promptly and diligently when he or she becomes aware of a mistake, accident or inadvertence. This simply stands to reason. Since a disclaimer requires that there must have been "mistake, accident or inadvertence … without any willful intent to defraud or mislead the public" under section 48 of the Patent Act, finding a duty of good faith requirement with respect to filing a disclaimer is generally consistent with the Patent Act. The Court found there to be no bona fide evidence of an actual "mistake, accident or inadvertence" to satisfy the requirements of section 48 of the Patent Act in the Other courts have rejected placing a more general duty of good faith on patent applicants. In Bourgault Industries Ltd. v. Flexi-Coil Ltd. (1999), 86 C.P.R. (3d) 221, Flexi-Coil alleged that the patent was invalid by reason of lack of candour for the applicants' failure to inform the Patent Office of a prior art machine which, according to the trial judge, had significant importance in the argument on validity of the patent. The Federal Court of Appeal rejected Flexi-Coil's argument and refused to extend a duty of disclosure on patent applicants beyond what the Patent Act, Patent Rules and jurisprudence already required. Justice Shore of the Federal Court in Janssen-Ortho v. Apotex, 2008 FC 744, also rejected the notion that there is a general duty of candour during patent prosecution, stating "[i]t is clear that there is no express duty of candour contained in the Patent Act or the Patent Rules and that the word “candour” does not even appear in this legislation. While a duty of candour and good faith exists during the prosecution of patent applications in the United States Patent Office, a similar In Weatherford Canada Ltd. v. Corlac, 2010 FC 602, Justice Phelan agreed there is a duty to act in good faith in dealing with the Patent Office, but found section 73(1)(a) would require the matter at issue to be raised in a requisition by the examiner. Justice Phelan also cited the passage of the Federal Court of Appeal in Bourgault which rejected the notion that a patent can be held invalid for an alleged breach of the duty of candour which goes beyond compliance with the Based on the current decisions, the most that can be said is that the law is unsettled as to whether there is an extended duty of candour and good faith in patent prosecution. But since the law is unsettled, a breach of the duty of candour or duty of good faith may be pleaded and pursued to trial. On an interlocutory motion concerning pleadings amendments in Mycogen Plant Science v. Bayer Bioscience N.V., 2009 FC 1013, Justice Hughes considered his comments in G.D. Searle and Justice Shore's comments in Janssen-Ortho and wrote that "given the uncertainty of the state of the law as to the duty of candour", he could not find it plain and obvious that a plea of lack of candour could not succeed and accordingly he did not strike out the allegations. The twenty year monopoly that is granted is an extraordinary benefit conferred on the inventor at public cost. If the representations or disclosure on which the grant is based are not full, frank and fair, then the public, who are paying the monopoly price for the invention, may well hold the Courts responsible. While many of the decisions on lack of candour may not be egregious enough to cause our system of justice to fall into disrepute, a decision to uphold a patent when there has been conduct that may be offensive to public standards of integrity and honesty should 2. The U.S. Standard: Inequitable Conduct
In the United States, the Code of Federal Regulations provides that "each individual associated with the filing and prosecution of a patent application has a duty of candor and good faith in dealing with the Office … which includes a duty to disclose to the Office all information known to that individual to be material to patentability as defined in this section."7 Breach of this duty is considered inequitable conduct. Inequitable conduct is found where there is clear and convincing evidence of a material misrepresentation that is intentionally made. A finding of inequitable conduct will give the court the discretion to invalidate the patent. Materiality is defined by Rule 56 of the Code of Federal Regulations. Material information is defined as information that is not cumulative to other information and establishes a prima facie case of unpatentability or refutes or is inconsistent with an applicant's argument. A material reference does not need to be an invalidating reference as the Federal Circuit has stated that a "reasonable examiner may find a particular piece of information important to a determination of patentability, even if that piece of information does not actually invalidate the patent."8 Overstatements and exaggerations about a reference, however, have not been found material as the examiner had the reference and could consult it while evaluating the patent applicant's 8 Avid Identification Systems v. The Crystal Import, Slip. Op. (April 27, 2010 Fed. Cir.). statements about it.9 Moreover, the Federal Circuit has said "[g]overnment officials are presumed to have properly discharged their official duties" and "if the references were in front of the examiner, it must be assumed that he or she reviewed them."10 The intent to deceive standard requires a specific intent to deceive the Patent Office by misrepresenting or withholding a material fact.11 Smoking gun evidence is not required; intent to deceive may be inferred based on the fact and circumstances surrounding the applicant's overall conduct.12 It is easier to infer intent to deceive where the information not disclosed is highly material. A conscious decision to deceive the Patent Office about a material fact must have been made. Oversight, poor judgment, error, negligence or even gross negligence is not sufficient. 13 Although there is a significant amount of jurisprudence on inequitable conduct in the U.S., the statutory duty of a patent applicant in the U.S. to disclose to the Patent Office all information known to that individual to be material to patentability is a duty with no statutory equivalent in Canadian law. That difference alone will often raise questions as to the applicability of U.S. case law to the duty of good faith under section 73(1)(a) of Patent Act in Canada. 3. Best Practices for Practitioners
A. Best Practices for Patent Prosecutors
Section 35 of the Patent Act requires the Commissioner of Patents to cause patent applications to be examined by competent examiners employed in the Patent Office. In replying a requisition from the Patent Office, however, applicants and their agents must ensure what they say is fair 9 Gambro Lundia v. Baxter Healthcare, 110 F. 3d 1573, 1581 (Fed. Cir. 1997). 10 In re Portola Packaging, 110 F. 3d 786, 790 (Fed. Cir. 1997). 11 Kingsdown Med. Consultants v. Hollister, 863 F. 2d 872 (Fed. Cir. 1988). 12 Paragon Podiatry Lab v. KLM Lab., 984 F. 2d 1182, 1189 (Fed. Cir. 1993). 13 Kingsdown Med. Consultants v. Hollister, 863 F. 2d 872 at 872-873 (Fed. Cir. 1988). and accurate in view of information which is known or ought to be known (such as through Applicants and their agents should avoid making sweeping statements about the prior art. Prior art referred to should be specifically identified and should never be referenced "as a whole". Care should be taken to describe prior art correctly and to consider each cited prior art reference in its entirety. Arguing excerpts specifically referenced by the Examiner and failing to discuss other more relevant portions of the reference could be found to lack good faith. Moreover, voluntary disclosures of prior art should be made carefully. Mentioning certain prior art references while omitting mention of more material prior art references could be perceived to be lacking in good faith. If information is to be volunteered, it is best to be full, frank and fair in Preferably, the agent responding to a requisition should be aware of the prior art cited by an examiner against corresponding applications in foreign jurisdictions on the issues of novelty and The applicant's agent should also take care that the differences between the invention and the cited references are in fact differences reflected in the invention as claimed. Arguments which succeed in persuading an examiner to allow an application which argue the presence or advantages of elements not found in the claims might be found to lack good faith. If a misrepresentation is made in reply to a requisition by mistake, accident or inadvertence, the applicant ought to consider what steps can be taken to remedy the situation. If the application is still in prosecution, the mistake should be brought to the attention of the Examiner as soon as possible prior to issuance of the patent. If the patent has already issued, the materiality of the misrepresentation ought to be evaluated and a request for re-examination should be considered if the misrepresentation was related to prior art. Prior uses, prior sales and other non-patent disclosures by the applicant that might be seen as material to the patentability of the claims should also be considered. Preferably, description of these disclosures should be made in the background section of the patent application so as to avoid a finding similar to that made by Justice Hughes in the G.D. Searle decision. Care should be taken not to disclose any additional information over what had been previously disclosed. B. Best Practices for Patent Litigators
As discussed above, the duty of good faith is on the patent applicant. Clearly, all statements made in responding to a requisition from the Canadian patent examiner ought to be reviewed with respect to whether the statements were full, fair and frank. If there are corresponding foreign patent applications, their file histories may be relevant to evaluate whether statements made before the Canadian examiner were in good faith. Investigation as to whether there has been any litigation, re-examination or other proceedings concerning the patent at issue, a corresponding patent, or a related patent may provide evidence of what information was known to the applicant when it responded to requisitions from the Canadian patent examiner. These proceedings may contain information as to the prior art or material facts known to the applicant at the time it responded to the requisitions. Lastly, due to the uncertainty in the law in the area, all other steps taken by the applicant in dealing with the Patent Office should be considered with respect to whether a breach of a general or extended duty of good faith or duty of candour may be fairly alleged. 4. Conclusion
The law on the duty of good faith in patent prosecution is still in its infancy in Canada. While it is clear that a duty of good faith exists in disclosing the invention in the specification (s. 53(1)) and in responding to a requisition by an examiner in the examination of a patent application (s. 73(1)(a)), it is not yet settled whether a duty of good faith or a duty of candour arises in other circumstances. In view of this uncertainty, patent litigators may choose to allege a breach of the duty of good faith in wide-ranging circumstances until the jurisprudence becomes better-defined.

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