Double Patenting

The term double patenting does not appear in the Patent Act. However, according to subsection 36(1) an inventor is entitled to a patent for each invention.

Patent for one invention only

36 (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. [Emphasis added.]

The Supreme Court of Canada found support for the prohibition against double patenting in subsection 36(1) of the Patent Act.

63 The prohibition against double patenting relates back to the evergreen problem mentioned at the outset. The inventor is only entitled to a patent for each invention: Patent Act, s. 36(1). If a subsequent patent issues with identical claims, there is an improper extension of the monopoly. It is clear that the prohibition against double patenting involves a comparison of the claims rather than the disclosure, because it is the claims that define the monopoly. The question is how identical the claims must be in the subsequent patent to justify invalidation.

The legislative foundation of the doctrine of double patenting has been questioned on the basis that subsection 36(1) of the Patent Act is limited to divisional applications and situations where multiple inventions are claimed in one patent. The Federal Court rejected this argument on the basis that double patenting is indisputably an accepted ground of invalidity and it is entirely consistent with the intent and purpose of the Patent Act, which is to prevent evergreening.

[123] Double patenting is a judge-made doctrine of invalidity which rests on the notion that an inventor is only entitled to one patent for each invention. This doctrine, which has been grounded in subsection 36(1) of the Patent Act and is devised to prevent the evergreening of patents, has been recognized by the Supreme Court for many years: Whirlpool Corp v Camco Inc, 2000 SCC 67, [2000] 2 SCR 1067, at paras 63ff [Whirlpool]; Apotex Inc v Sanofi-Synthelabo Canada Inc, 2008 SCC 61, [2008] 3 SCR 265, at paras 95-97 [Sanofi-Synthelabo]; see also Aventis Pharma v Pharmascience, 2006 FCA 229, at para 67. Lilly questioned the legislative foundation of that doctrine, contending that subsection 36(1) of the Patent Act relates only to divisional applications and only addresses situations where more than one invention is claimed in one patent. Whatever may be the merit of this textual argument, it is now beyond dispute that double patenting is an accepted ground of invalidity, and it is entirely consistent with the intent and purpose of the Patent Act, which is to prevent the undue extension of the statutory monopoly of a patent by means of a series of patents with obvious or uninventive additions. …

In Farbwerke Hoechst, the patentee had obtained a patent relating to a medicine and sought another patent for the medicine in diluted form. The Supreme Court of Canada observed that there was no further invention, because there there was no novelty and inventive ingenuity in the procedure of dilution. The diluted and undiluted substance were two aspects of exactly the same invention. The patentee had already received patent protection to the full extent allowed by the law. The Commissioner of Patents was well founded in rejecting the additional patent.

What the respondent is seeking can be put in very plain words. It has a patent under s. 41 for the invention of the medicine. It now wants another patent for the medicine in a diluted form … that will enable it to be put on the market for consumption.

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The Exchequer Court went on to hold that the antidiabetic composition was new and useful and therefore patentable. It also held that there was inventive ingenuity.

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The fallacy in the reasoning is in the finding of novelty and inventive ingenuity in this procedure of dilution.

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A person is entitled to a patent for a new, useful and inventive medicinal substance but to dilute that new substance once its medical uses are established does not result in further invention. The diluted and undiluted substance are but two aspects of exactly the same invention.

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Further, the respondent has already received patent protection to the full extent allowed by the law. Invention may lie in a new, useful, and inventive process for producing a new medicinal substance, and the respondent has already obtained patents for such inventive processes and for the new product as produced by such processes. The process claims and process dependent product claims in these patents represent the full extent of the protection to which the respondent is entitled.

Therefore, the primary error in the judgment of the Exchequer Court is twofold. The mixing of a patented chemical substance with a carrier is not new and it is not the result of inventive ingenuity.

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I am therefore of the opinion that the rejection of the application by the Commissioner of Patents was well founded for the reasons stated by him in his letter of rejection, which I now set out in full:

… The applicants are entitled to only one patent for their invention. The compositions defined in the claims fail to inventively distinguish from the product claims appearing in parent application number 708,643 now Patent number 582,621. The composition claims are obviously directed to the same invention as the product claims of Patent 582,621. …

Justice Dickson (as he then was) referred to the decision of the Supreme Court of Canada in Farbwerke Hoechst as the main authority on double patenting, standing for the proposition that a second patent could not be justified if the claims exhibited no ingenuity or novelty over the first patent.

In response to this argument, the respondent cites the judgment of this Court in Commissioner of Patents v. Farbwerke Hoechst Aktiengesellschaft Vormals Meister Lucius & Bruning [[1964] S.C.R. 49], the main authority on double patenting. In that case the applicant had already patented an anti-diabetic medicine. It now wished to patent a second one composed of that medicine plus an inert carrier. Judson J. for the Court said that the second process involved no novelty or ingenuity, and hence the second patent was unwarranted.

[Footnote incorporated; p. 536]

In Whirlpool, the Supreme Court of Canada explained that the prohibition against double patenting relates to evergreening, which, contrary to the bargain between the patentee and the public, improperly extends a monopoly beyond what the public has agreed to pay.

37 It is common ground that the bargain between the patentee and the public is in the interest of both sides only if the patent owner acquires real protection in exchange for disclosure, and the public does not for its part surrender a more extended monopoly than the statutory 17 years from the date of the patent grant (now 20 years from the date of the filing of the patent application). A patentee who can evergreen a single invention through successive patents by the expedient of obvious or uninventive additions prolongs its monopoly beyond what the public has agreed to pay. The issue is whether Whirlpool’s ’734 patent falls into that condemned category.

The Supreme Court of Canada in Sanofi put the concern about evergreening this way:

[97] Evergreening is a legitimate concern and, depending on the circumstances, strategies that attempt to extend the time limit of exclusivity of a patent may be contrary to the objectives of the Patent Act. The Act aims to promote inventiveness by conferring exclusivity for a limited period of time while providing for public disclosure of the invention to enable others to make or use it after expiry of the period of exclusivity.

In Whirlpool, the Supreme Court of Canada observed that a double patenting inquiry involves a comparison between the claims of two patents, not a comparison of the disclosure.

63 It is clear that the prohibition against double patenting involves a comparison of the claims rather than the disclosure, because it is the claims that define the monopoly.

The Court also addressed the question of just how close the claims must be to justify invalidation of the subsequent patent. The Court identified two tests, which it referred to as branches of the prohibition on double patenting. In the first branch, same invention double patenting, the claims must be identical or coterminous. In the second branch, obviousness double patenting, which is broader, the later patent has claims that are not patentably distinct from those of the earlier patent, or involve no novelty or ingenuity.

64 The Federal Court of Appeal has adopted the test that the claims must be identical or conterminous: Beecham Canada Ltd. v. Procter & Gamble Co. (1982), 61 C.P.R. (2d) 1, at p. 22. This verbal formulation derives from an editorial comment by Dr. H. G. Fox, Q.C., on Lovell Manufacturing Co. v. Beatty Bros. Ltd., reported at (1962), 23 Fox Pat. C. 112, at pp. 116-17:

Letters patent are not granted at pleasure, but for a term of years and the grant of a second patent with respect to the same subject-matter would be void under this statute [6 Henry VIII, c. 15, 1514] and by the Statute of Monopolies, as well as at common law and by the terms of section 28(1)(b) of the Canadian Patent Act. But for this purpose the subject-matter of the two grants must be identical. A subsequent claim cannot be invalidated on the ground of prior claiming unless the two claims are precisely conterminous.

65 This branch of the prohibition on double patenting is sometimes called same invention double patenting. Given the claims construction adopted by the trial judge it cannot be said that the subject matter of the ’734 patent is the same or that the claims are identical or conterminous with those of the ’803 patent.

66 There is, however, a second branch of the prohibition which is sometimes called obviousness double patenting. This is a more flexible and less literal test that prohibits the issuance of a second patent with claims that are not patentably distinct from those of the earlier patent. In Commissioner of Patents v. Farbwerke Hoechst Aktiengesellschaft Vormals Meister Lucius & Bruning, [1964] S.C.R. 49, the issue was whether Farbwerke Hoechst could obtain a patent for a medicine that was a diluted version of a medicine for which it had already obtained a patent. The claims were neither identical nor conterminous. Judson J. nevertheless held the subsequent patent to be invalid, explaining at p. 53:

A person is entitled to a patent for a new, useful and inventive medicinal substance but to dilute that new substance once its medical uses are established does not result in further invention. The diluted and undiluted substance are but two aspects of exactly the same invention. In this case, the addition of an inert carrier, which is a common expedient to increase bulk, and so facilitate measurement and administration, is nothing more than dilution and does not result in a further invention over and above that of the medicinal itself. [Emphasis added in Whirlpool.]

67 In Consolboard, supra, Dickson J. referred to Farbwerke Hoechst as the main authority on double patenting (p. 536) which stood for the proposition that a second patent could not be justified unless the claims exhibited novelty or ingenuity over the first patent:

Judson J. for the Court said that the second process involved no novelty or ingenuity, and hence the second patent was unwarranted.

In the passage below, Justice Hughes noted the distinction between invalidity on the basis of obviousness double patenting and invalidity on the basis of obviousness.

[124] What is important to keep in mind is that the exercise required in the inquiry as to whether there is double patenting is that the claims of the earlier patent owned by the same patentee as the latter must be compared with the claims of the latter to see if they are identical or co-terminus, or whether the latter is obvious in view of the former. Therefore, the exercise is somewhat different than that of dealing with obviousness of a patent having regard to the art that would have been known to a person skilled in the art as of the relevant time. The exercise respecting double patenting is to present the notional person skilled in the art with the claims of the first patent and inquire whether what is claimed in the second patent was identical or co-terminus with the first or would have been obvious in light of the earlier patent. The inquiry must not bother with any inquiry as to whether the earlier patent would have come to the attention of the notional person skilled in the art. Nor does the inquiry extend to the validity or otherwise of the claims of the earlier patent. Nor does the inquiry extend to prior art beyond the earlier patent, as Binnie J. wrote at paragraph 67 of Whirlpool, the inquiry is whether a second patent can be justified unless the claims exhibit novelty or ingenuity over the first patent. As the Supreme Court of Canada, Binnie J. said in another case, Apotex Inc. v. AstraZeneca Canada Inc., [2006] 2 S.C.R. 560 at paragraph 39, there is an evident (and entirely understandable) commercial strategy of the innovative drug companies to evergreen their products by adding bells and whistles to a pioneering product even after the original product for that patent has expired. This is the evergreening problem discussed in Whirlpool, supra.

[Emphasis in original.]

After reviewing the relevant jurisprudence, Justice Gleason laid out a three-step inquiry for assessing a claim of double patenting.

[68] Thus, to recap, in order to assess a claim of double patenting, the court must undertake the following three-step inquiry:

• First, it must set out what is claimed in each of the patents, construing the claims, if necessary;
• Second, the court must determine if the claims in the two patents are identical. If they are and the same invention is claimed, the second patent will be void for same invention or coterminous double patenting; and
• Finally, if the inventions claimed in the two patents are not identical, the court must then go on to determine if the invention claimed in the later patent is inventive or patentably distinct from the invention claimed in the earlier patent. If not, then the second patent will be void for obviousness-type double patenting.

The Federal Court of Appeal summarized the law on double patenting as follows:

[26] The double-patenting doctrine holds that a claim is invalid if it constitutes patenting of an invention that has already been claimed in a previous patent. It is aimed at the problem of evergreening; extending the monopoly that was granted on the first patent by filing a new patent that does not offer a new invention to the public. As such, the doctrine of double-patenting prevents a patentee from violating the bargain at the heart of the patent system.

[27] In Whirlpool, the Supreme Court of Canada recognised two types of double-patenting. The first is same-invention double-patenting, which occurs when the claims of the second patent are outright identical or coterminous to the first. This is not alleged in this case. The second is obviousness-type double-patenting, which occurs when the second patent is not identical to the first, but is nonetheless not patentably distinct from the first.

[28] Invalidity on the basis of obviousness-type double-patenting is not the same as invalidity on the basis of obviousness. Obviousness is directed at the question of whether an invention (in the legal sense) exists at all. Obviousness-type double-patenting has a different policy justification; the prevention of evergreening an existing patent through what would otherwise be a valid patent but is, in effect, an extension of the patent that has already been granted: Merck & Co., Inc. v. Pharmascience inc., 2010 FC 510, at para. 124, 368 F.T.R. 1. Some of the differences are contested issues in this appeal, but a few uncontroversial distinctions between the two variants of the doctrine can be noted.

[29] In an obviousness challenge, any piece of prior art, including a collection of works, can be cited as rendering the impugned patent obvious and therefore not patentable: Sanofi-Synthelabo at paras. 67-71. By contrast, in an obviousness-type double-patenting challenge, only the earlier patent can be cited as rendering the impugned patent not patentably distinct; any other prior art is only relevant insofar as it contributes to the common general knowledge of the skilled person.

[30] Finally, in an obviousness challenge, subsection 28.3(a) of the Patent Act provides that any information disclosed by the patentee within a year prior to the filing cannot be cited as prior art that renders the patent obvious. This effectively gives the patentee a one-year grace period before filing in which it can make disclosures without worrying that those disclosures will be the basis of an obviousness attack. Double-patenting is not subject to subsection 28.3(a), which is what allows the earlier patent to be cited if it was published within a year of the filing date of the impugned patent.

Justice Hughes explained that it is only when the further patent was applied for at a time when the first patent cannot serve as prior art that double patenting becomes an issue. In other words, double patenting may become an issue only when the first patent is not citable against the second patent for anticipation or obviousness under sections 28.2 and 28.3 of the Patent Act, respectively.

[140] Double Patenting gives expression to the concept that the same person should not be able to extend the monopoly which it has in respect of a patent, by securing a further patent that covers the same claimed invention or an obvious equivalent. If the first patent was published sufficiently before the application for the further patent, then it will simply serve as a piece of prior art and the further patent may be invalid for lack of novelty or obviousness. Thus, it is only when the further patent was applied for at a time when the first patent cannot serve as prior art that double patenting becomes an issue. Obviously, both patents must be owned by the same patentee.

In Ramipril I (FCA), an allegation of double patenting was made even though the patents at issue had different inventors and were issued to different corporations. The Federal Court of Appeal stated that given that the inventors worked independently, it could not reasonably be found in this case that there was an attempt to extend the terms of the patents.

[66] It is unnecessary to consider whether the Judge was correct to conclude that the doctrine of double patenting is not limited to cases involving a single inventor. However, since the point was fully argued, I will discuss it. …

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[70] Aventis and Schering argue that the doctrine of double patenting cannot apply unless there are multiple patents issued to the same inventor. In this case, the inventor of the ’206 patent is not the same as the inventor of the ’087 or ’457 patents. …

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[72] … Given that the inventors of the ’087 and ’457 patents were working independently of the inventor of the ’206 patent, it cannot reasonably be found in this case that the filing of the application for the ’206 patent was an attempt to extend unduly the term of the ’087 patent and the ’457 patent. …

The Court refused to adopt the proposition that double patenting can never apply unless the patents issued to the same inventor. According to the Court, the doctrine of double patenting, as a set of judge-made rules, should be left to evolve on a case-by-case basis.

[73] That is not to say that I would be prepared at this point to adopt the proposition that double patenting can never apply unless there is a single inventor. Although it is difficult at this point to envisage a case involving more than one inventor that is or should be vulnerable to a claim of double patenting, I see no reason to foreclose such a possibility. In my view the doctrine of double patenting, as a set of judge-made rules, should be left to evolve on a case-by-case basis.

Justice Hughes noted that double patenting involves the same parties, such as inventors or applicants.

[206] Double patenting is a judge - made concept. It does not appear in the Patent Act. The Patent Act in this regard in section 27 states that a patent will be invalid only if there has been a disclosure of the invention at least a certain period of time in advance of the filing of the application for the patent under consideration. No such period of time exists here.

[207] Double patenting deals with a situation where there is insufficient time between prior disclosure and filing or where several patents issue from the same application (divisionals) and the same parties such as inventors or applicants are involved. The theory is that a person should not enjoy an extended monopoly in the same invention by having separate patents issued to it when there really is only one invention involved.

Justice Rothstein remarked that evergreening does not arise when a selection patent is sought by a party other than the inventor or owner of the original genus patent.

[98] However, a generalized concern about evergreening is not a justification for an attack on the doctrine of selection patents for two reasons. First, a selection patent may be sought by a party other than the inventor or owner of the original genus patent. In such a case, anticipation or obviousness may be an issue, but evergreening does not arise.

The Federal Court observed that jurisprudence subsequent to Ramipril I (FC) in 2005 has consistently assumed that double patenting can only arise where the two patents are owned by the same parties.

[341] I also observe that the inventors and owners of the ’087 Patent are different from the inventors and owner of the ’206 Patent. There is no corporate relationship between the owners of the respective patents. The fact that Sanofi Deutschland, the successor of the original owner of the ’087 Patent, is a licensee under the ’206 Patent, appears to be irrelevant to any question of double patenting. Although I considered and rejected the notion that double patenting could only exist where patents are owned by the same parties (see Ramipril I (FC), at para. 59), subsequent jurisprudence has consistently assumed that double patenting can only arise where the two patents are held by the same parties (see Merck v. Apotex, 2006 FC 524, 53 C.P.R. (4th) 1, at para. 207; Apotex Inc. v. Sanofi-Synthelabo Canada Inc., 2006 FCA 421, 59 C.P.R (4th) 46 at para. 45, aff’d 2008 SCC 61). In Bristol Myers v. Apotex, 2009 FC 137 at paragraph 174, Justice Hughes described the applicability of double patenting as follows:

Double patenting only applies when dealing with the same person getting two or more patents. If some other person has received an earlier patent, then the second patent is to be considered in the context of anticipation and obviousness or, in the case of pre-October 1989 patent applications, the first to invent.

Double patenting may be asserted as a ground of invalidity even where there is no evergreening.

For instance, under the current Patent Act, divisional patent applications have the same filing date as the corresponding parent applications. In this scenario, evergreening does not occur since the divisional patent and parent patent will expire on the same date. Even so, double patenting may be asserted as a ground of invalidity.

In Glaxosmithkline, the two patents at issue had the same filing date, as one of the patents was filed as a divisional application of the other patent, and therefore there was no evergreening. The patentee argued that since there was no evergreening, which had been cited as the rationale for preventing double patenting, the divisional patent could not be found invalid on account of double patenting.

89. Counsel for GSK argued at the hearing that under the post-1989 provisions of the Act, a patent made as a divisional application cannot be found invalid on account of double patenting. The reason, to use the words of counsel, is that the sin of double patenting was removed by the 1989 amendments. Under the pre-1989 provisions, patent protection ran from the date of issue, meaning that the issuance of a second patent would grant the holder a renewed protection period. This practice is commonly referred to as evergreening and has been cited as the rationale for preventing double patenting, see Whirlpool at paragraph 63 (the decision dealt with the pre-1989 version of the Act). As a result of the 1989 amendments to the Act, patent protection now runs from the date of filing, not the date of issue. Divisional applications share the same filing date under subsection 36(4) and no additional protection is gained by the existence of the second patent. GSK drew an analogy to American patent law, where a second patent is not invalid for double patenting if the patent holder gives up the period of additional protection by making a terminal disclaimer, see In re Bowers, 53 C.C.P.A. 15, 359 F.2d 886 (1966), In re Plank, 55 C.C.P.A. 1400, 399 F.2d 241 (1968) and In re Kaplan, 789 F.2d 1574 (Fed. Cir. 1986).

The Federal Court rejected this argument and concluded that, regardless of whether there is evergreening, a patent holder should not be able to receive additional patents for the same invention since inventive ingenuity was still needed to support the second patent.

91. Furthermore, regardless of whether the sin of double patenting still exists, a patent holder should not be able to receive additional patents for the same invention. Support for this position can be found in the decision of Lutfy J. (as he then was) in Bayer Inc. v. Canada (Minister of National Health and Welfare) (1998), 154 F.T.R. 192, 82 C.P.R. (3d) 359, aff’d (2000) 6 C.P.R. (4th) 285 (F.C.A.). Bayer had two patents, filed as divisional applications, that covered the same invention. The period of patent protection ran from the date of issue and the term of the second patent ran for an additional eighty months after the expiry of the initial patent. Bayer later made a terminal disclaimer that brought the expiry date of the second patent in line with that of the first. Bayer argued that the second patent was not invalid for double patenting because the terminal disclaimer had removed the harm of double patenting. The argument was rejected by Lufty J., who held that inventive ingenuity was still needed to support the second patent. I agree. As Binnie J. noted in Whirlpool at paragraph 63, subsection 36(1) of the Act states that an inventor is only entitled to a patent for each invention. The logical extension of this is that two inventions are required to support two patents. This is confirmed by the wording of subsection 36(2).

Double patenting is not an accepted ground of invalidity where the divisional application was submitted due to the direction of the Patent Office.

As I noted earlier, the appellant originally filed a single patent application for letters patent, but was required by the Commissioner of Patents to divide his application into two parts. It may be open to question whether the Commissioner of Patents should have split off the wafers and treated them as the subject of a separate patent but in my view a patentee is not to be prejudiced by enforced divisional applications. If patents are granted on divisional applications directed by the Patent Office, none of them should be deemed invalid, or open to attack, by reason only of the grant of the original patent. [pp. 536-537]

As illustrated in the passage below, the date chosen for assessing obviousness double patenting can be determinative of the inquiry. This is because the common general knowledge of the person skilled in the art is relevant in assessing obviousness double patenting, and that knowledge can advance over time.

[71] Second, they disagree as to the date at which the obviousness-type double patenting inquiry is to be conducted. Lilly says it should be undertaken at January 21, 1994, the priority date of the 377 Patent, the earlier of the two relevant patents in this case. Apotex, on the other hand, argues that it should be undertaken at February 6, 1997, the publication date of the 784 Patent, the later of the two relevant patents in this case. They, however, agree as to the outcome of the analysis undertaken at each of these dates.

[72] More specifically, if the relevant date for purposes of the inquiry is the earliest possible one, i.e. January 21, 1994, the priority date of the 377 Patent, Apotex conceded in oral argument that the claims of the 784 Patent would not be obvious over the claims of the 377 Patent because the common general knowledge of the skilled person — through whose eyes the Patents are to be construed — had not advanced enough to render the claims of the 784 Patent obvious by January 21, 1994.

[73] On the other hand, if the relevant date for assessing obviousness-type double patenting is the latest possible one posited, i.e. February 6, 1997, the publication date of the 784 Patent, Lilly does not contest that the claims in the 784 Patent would be void for obviousness-type double patenting and, indeed, called no evidence to counter Apotex’ expert evidence that the common general knowledge of the skilled person to whom the 784 Patent is addressed had advanced to such a degree by February 1997 so as to render the claims of the 784 Patent obvious.

Justice Manson of the Federal Court reviewed the jurisprudence regarding the appropriate date at which double patenting is to be analyzed and concluded that it is the priority date of the second patent.

[207] There was significant argument over which date should be relevant to the double patenting analysis: the claim date of the first patent (First Filing), the priority date of the second patent (Second Priority), or the publication date of the second patent (Second Publication).

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[212] … [T]he law as it currently exists on the appropriate date for the obviousness-type double patenting analysis is inconclusive.

[213] In light of Justice Rennie’s explicit comments regarding the suitability of the Second Publication date, I find that the Respondent’s main submissions regarding the date, while persuasive based upon the principles underpinning obviousness-type double patenting, cannot succeed. However, I note that Justice Pelletier suggested an alternative framework for assessing obviousness-type double patenting that appears to effectively place the date of the analysis at the Second Publication date, since claim construction is to be done as of the publication date of each patent (Apotex Tadalafil FCA at para 40):

Perhaps, the Court, having construed the claims of each of the patents with the assistance of the persons skilled in the art, simply compares the claims and decides whether the later claims are patentably distinct from the earlier claims on the basis of the insights which it has gained in the course of the construction of the patents.

[214] In obviousness-type double patenting, the impermissible evergreening concerns the addition of non-inventive bells and whistles to the first patent. Assessing the whether or not the claims of the two patents are patentably distinct as of that earlier date would exclude amendments, particularly use amendments, that become obvious at a later date through the evolution of the common general knowledge. It would be idiosyncratic for a subsequent patent to be obvious when compared to the first, but not an example of obviousness-type double patenting.

[215] As such, I agree with the comments made by Justice Mary Gleason in Eli Lilly Canada Inc v Apotex Inc, 2015 FC 875 [Eli Lilly Tadalafil] at paragraph 132:

Particularly in the context of pharmaceutical patents involving a new use for an existing compound or class of compounds, there could be a situation where the common general knowledge advances after the claim date of the first patent that would render the new use claimed in the second patent obvious as of the claim date in the second patent, resulting in the later patent being an impermissible evergreening through extension based on obvious amendments to the initial patent. In such circumstance, I believe a sound argument may be made for the selection of the priority date of the second patent as being the date in respect of which the assessment of obviousness-type double patenting should be undertaken.

[216] Based upon my finding that the Second Priority date is the appropriate date at which double patenting is to be analyzed, I find that the Respondent’s allegations of double patenting are justified for both claim 1 and claim 3 of the ’898 Patent.