AstraZeneca AB v Intas Pharmaceuticals Limited (2020)

Summary

“IN 147, as per the averments made in the plaint, is the genus patent while IN 625 is claimed to be the species patent. The moot point, which arises for consideration in the instant actions, is: whether the compound-in-issue i.e. Dapagliflozin … which, according to the plaintiffs, is covered in IN 147 stands disclosed both, in law as well as on facts?” (para 2) “The plaintiffs claim that DAPA” (“Dapagliflozin”) “is used worldwide to treat people suffering from type-II diabetes mellitus.” (para 3.3) “The prayers made in the suit actions including the captioned interlocutory applications seek injunction against purported infringement of not only IN 147 but also of IN 625. The suit actions were filed on 30.09.2020 i.e. two days prior to expiry of validity period of IN 147” (para 14).

The Court held that “even when the patent crosses the threshold of examination by the patent office, it does not, as per the Statute, warrant its validity” (para 18.1), and that “all that the defendant is required to demonstrate is that she/he has made a credible challenge or that the patent is vulnerable” (para 19.2). It held: “It seems incongruous to me that a patent holder can take out an infringement action for a patent and yet aver it is not disclosed.” (para 22) It held that “the defendants’ submission that IN 625 should be revoked on account of prior claiming under the provisions of Section 64(1)(a) of the Act has substance” (para 22.2), that “there is no technical advance of the latter over the former” (para 29.3), that the US examination report and the plaintiffs’ response “were vital documents which ought to have been furnished to the Indian Patent Office” (para 32.2), and that “the scales of balance, in my opinion, at this stage, would weigh in favour of the defendants” (para 38.1). “Thus, for the foregoing reasons I am not inclined to grant an injunction in favour of the plaintiffs and against the defendants. Consequently, the captioned applications are dismissed.” (para 40)

What the court decided

1. No presumption of validity. “In this context, subsection (4) makes it clear that examination and investigations required under Section 12 or Section 13 shall not be deemed, in any way, to warrant inter alia the validity of the patent. In other words, even when the patent crosses the threshold of examination by the patent office, it does not, as per the Statute, warrant its validity. Therefore, quite clearly, irrespective of when the challenge is laid, the challenger … can put the patent in jeopardy.” (para 18.1) For this the Court relied on Bishwanath Prasad Radhey Shyam v Hindustan Metal Industries (1978), setting out the Supreme Court’s words that “this position viz. the validity of a patent is not guaranteed by the grant, is now expressly provided in Section 13(4) of the Patents Act” (para 18.1, footnote 1). “Thus, till the time the patent is invalidated i.e. revoked, the patentee has the right to exclude third parties. Therefore, the observations made in Pfizer Inc. and Ors. case and Telefonaktiebolaget LM Ericsson (PUBL) case cannot, in my view, be read in a manner whereby they roil against express provisions of the statute.” (paras 18.1–18.2) “Furthermore, the argument advanced on behalf of the plaintiffs that since the suit patents are old and thus, should be presumed to be valid cannot be accepted for two reasons.” “First, there is a period of overlap between the genus patent i.e. IN 147 and the species patent i.e. IN 625. The defendants, in this case, chose to wait … till such time the validity period of the genus patent i.e. IN 147 expired.” “The presumption of validity exists only till such time the patent is challenged - a challenge which is credible and no further. In my opinion, if the plaintiffs’ argument was to be accepted, then, it would have to be held that the older the patent, the stronger the firewall. Such an interpretation, in my view, would be contrary to the plain words of the Statute.” (para 18.3) “Second, as indicated above, the scheme of the Act does not foreclose the right of the defendants in defence to an infringement action to question the validity of the patent. Section 107 of the Act, expressly confers a right on the defendants to raise, in defence, in an infringement suit, all those grounds on which the patent can be revoked under Section 64 of the very same Act. Therefore, the judgement in Bristol-Myers Squibb Company and Ors vs. J.D. Joshi and Ors., MANU/DE/1889/2015, if read in context, would demonstrate that it has not emasculated the right of the defendant, as conferred under the Act, to challenge the validity of the patent.” (paras 18.1–18.3)
2. The threshold at the interim stage. “The next question which arises for consideration is: at the stage of preliminary injunction, what is the threshold that the challenger has to meet?” (para 19) Of F Hoffmann-La Roche v Cipla (2009) the Court said: “The Court, in no uncertain terms, stated that validity of a patent is required to be looked at the stage of trial.” (para 19.1) “However, at the stage of preliminary injunction all that the defendant is required to demonstrate is that she/he has made a credible challenge or that the patent is vulnerable and that validity is not vexatious.” In the passage the Court extracted, the Division Bench had held that “the Court when faced with a prayer for grant of injunction and a corresponding plea of the defendant challenging the validity of the patent itself, must enquire whether the defendant has raised a credible challenge. In other words, that would in the context of pharmaceutical products, invite scrutiny of the order granting patent in the light of Section 3(d) and the grounds set out in Section 64 of the Patents Act 1970” and that “At the present stage of considering the grant of an interim injunction, the defendant has to show that the patent that has been granted is vulnerable to challenge.” (para 19.2) “This view has been reiterated in Natco Pharma vs. Bear Healthcare LLC, 2019 80 PTC 131 … and Natco Pharma vs. Bristol Myers Squibb Holding, 263 (2019) DLT 622” (paras 19–19.3)
3. Coverage and disclosure. “Therefore, the fact that both in the pleadings and in the aforementioned documents, there is a definitive assertion that DAPA” (“Dapagliflozin”) “is covered in both the genus patents granted in USA and India i.e. US 126 and IN 147 cannot be disputed.” (para 21.6) The Court also held that “The fact that IN 147 has been worked commercially in India cannot be disputed if one were to peruse Form 27 filed by the plaintiffs in consonance with the provisions of Section 146(2) read with Rule 131 of The Patent Rules, 2003” (para 21.2), and that “The fact that PTE” (“patent term extension”) “applications were moved for the extension of the term of US 117 is not in dispute.” (paras 21.2–21.6) “In my view, the fact that the plaintiffs have taken out an infringement action both for IN 147 and IN 625 is a sufficient clue, at least at this juncture, that DAPA is claimed in both suit patents. It seems incongruous to me that a patent holder can take out an infringement action for a patent and yet aver it is not disclosed.” (para 22) “This is especially so as under our Act the ‘complete specification’ provision encapsulated in various subclauses of subsection (4) of Section 10 require setting out by an applicant who seeks grant of patent to fully and particularly describe the invention and its operation or use and the method by which it is performed, disclose the method of performing the invention which is known to her/him and for which she/he is entitled to claim protection and end with a claim or claims defining the scope of the invention.” “The claim or claims forming part of complete specification inter alia are required to be ‘fairly based on the matter disclosed in the specification’” (paras 21.2–22.1)
4. Prior claiming. “Therefore, in my view, the defendants’ submission that IN 625 should be revoked on account of prior claiming under the provisions of Section 64(1)(a) of the Act has substance, at least at this stage.” (para 22.2) “What lends credence to this plea are the provisions of Section 13 (1) (b) of the Act which require the examiner to ascertain as to whether the application referred to him for investigation under Section 12 adverts to an invention which is anticipated by a prior claim. Section 13 (1) (b), simply put, allows an examiner to make use of an Indian patent application or an Indian patent which, though published, after the impugned patent bears a priority date which is earlier than the impugned patent. The fact that the said patent was published after the impugned patent does not come in the way of the investigation carried out by the examiner.” (para 22.3) “In the present case, the Indian genus patent i.e. IN 147 bears the priority dates 12.10.1999 and 05.04.2000 whereas the Indian species patent i.e. IN 625 bears 20.05.2002 as its priority date. For the purposes of Section 64(1)(a) this ingredient is sufficient. Therefore, as long as the defendant can establish that the inventions so far claimed in any claim of the complete specification … was claimed in a valid claim of an earlier priority date contained in the complete specification of another patent … – a ground for revocation is made out.” (paras 22.2–22.4)
5. Covered but not disclosed. “Furthermore, qua the arguments advanced on behalf of the plaintiffs that DAPA, though, covered in IN 147, was not disclosed therein, is answered, to my mind, by the judgement of the United Kingdom Supreme Court … in Regeneron Pharmaceuticals Inc (Respondent). vs. Kymab Ltd. (Appellant), (2020) UKSC 27” (para 24). Among the principles the Court extracted, the United Kingdom Supreme Court had held that “Patentees are free to choose how widely to frame the range of products for which they claim protection. But they need to ensure that they make no broader claim than is enabled by their disclosure.” (para 24.3) “Applying these principles, it would have to be said that the arguments of the plaintiffs that DAPA was not claimed in IN 147 seem to be untenable at this stage. The Regeneron Pharmaceuticals decision, in my opinion, has a greater persuasive value than the decisions rendered in Eli Lily, Apotex, 2010 FCA 214 and Dr. Reddy’s Laboratories (UK) Ltd vs. Eli Lilly and Co Ltd. (2009) EWCA 1362 cited on behalf of the plaintiffs, which are, distinguishable on facts.” (paras 24–25) “It must be stated that it was portrayed on behalf of the plaintiffs that the genus patent i.e. IN 147 ringfenced certain compounds which were disclosed only when the species patent i.e. IN 625 was granted, which would, essentially, mean that the written description/complete specification of IN 147 covered DAPA but did not disclose it. To my mind, such written descriptions/specifications would be flawed as it would prevent third parties from carrying out research in future. The Federal Court, in an en banc decision in Ariad Pharmaceuticals, Inc. vs. Eli Lilly and Company, 598 F.3d 1336, made some pertinent observations in this behalf.” In those observations, the Federal Court had said: “Such claims merely recite a description of the problem to be solved while claiming all solutions to it and, as in Eli Lilly and Ariad’s claims, cover any compound later actually invented and determined to fall within the claim’s functional boundaries—leaving it to the pharmaceutical industry to complete an unfinished invention.” (para 25.1) “In my opinion, given the aforesaid discussion, a credible defence to the infringement action is set up by the defendants.” (paras 24–26)
6. Anticipation by prior publication. “Concededly, the PCT publication date of IN 147 is 19.04.2001 which is well before, as noted above, the priority date of IN 625, that is, 20.05.2002.” (para 27) “In support of this submission, the defendants have, to a large extent, relied upon the affidavit of their expert witness i.e. one, Dr. Stephen F. Martin.” (para 27.3) “The plaintiffs, on the other hand, have relied upon an affidavit of one, Dr. Easwaran dated 18.10.2020” (para 27.4). The Court held: “Therefore, on this score, the defendants’ defence, at this stage, in my opinion, does not inject vulnerability.” (paras 27–28)
7. Technical advance over the genus. “A plain reading of the definition would show that it has two parts to it and both are inextricably linked with the other. In other words, if a patentee is unable to measure up to the ingredients of either of the two parts, the invention claimed is not construed under the Act as an inventive step.” (para 29.1) “First part involves patentee to show that the invention claimed in any claim involves ’technical advance’ as compared to the existing knowledge or has ’economic significance’ or both. The second part of the definition alludes to the fact that the invention should not be obvious to the person skilled in the art.” (paras 29.1–29.2) “A comparison of the complete specifications/descriptions of Indian genus patent i.e. IN 147 and Indian species patent i.e. IN 625 shows that there is no technical advance of the latter over the former. This is clearly evident if one were to peruse the following extracts from Indian genus patent i.e. IN 147 and Indian species patent i.e. IN 625.” (paras 29.1–29.3)
8. Post-priority evidence. “The plaintiffs sought to get over this by seeking to rely upon Dr. Washburn’s affidavit of April 2020 which was filed on 12.10.2020 to show technical advance.” (para 29.4) “In my opinion, if this information was not available at the time the application for grant of patent was filed, then, this cannot be taken into account, at this juncture, by the plaintiffs in support of their plea that IN 625 involved an inventive step. There is no clue in IN 625 of an unknown technical effect on its priority date. Dr. Washburn’s affidavit, who professes to be the co-inventor of DAPA, could have come to the rescue of the plaintiffs to demonstrate technical advance if, at least a seed of that nature had been planted in IN 625, on its priority date.” (para 30) In the passage the Court extracted from Generics (UK) Limited vs. Yeda Research and Development Company Limited, (2017) EWHC 2629 (Pat), that court had said that “such evidence can only be relied upon to confirm the existence of a technical effect which is plausible in the light of the specification and the skilled person’s common general knowledge, and not to establish the existence of a technical effect for the first time.” (para 30.3) “Therefore, what emerges is this: that post priority date evidence which has been furnished in Dr. Washburn’s affidavit to show technical advance can only be taken into account to confirm the existence of technical effect which is found embedded in the specification of IN 625 and is capable of being understood by a skilled person having common general knowledge and not to rely upon the same to establish its effect for the first time.” (paras 29.4–30.4)
9. Section 8 and the US prosecution. “Clearly the plaintiffs did not provide to the Indian Patent Office, the office action/examination report dated 30.07.2002 issued by the USPTO” (“US Patent Office”) “in connection with US 117 which corresponds to IN 625.” “It was only after terminal disclaimer was filed by the plaintiffs, which was accepted by USPTO, that US 117 was granted on 20.09.2002, albeit, with the caveat that it would expire on the same date as the US genus patent i.e. US 126. This information was not furnished to the Indian Patent Office.” (para 31) “In the instant actions, specific details were sought by the Indian Patent Office concerning search and examination report. What was submitted by the plaintiffs to the Indian Patent Office via the letter dated 10.01.2005 were the corresponding US patents and not the examination reports.” (para 32.1) “These were vital documents which ought to have been furnished to the Indian Patent Office.” (paras 31–32.2) “In my view, the judgement in Chemtura Corporation vs. Union of India (UOI) and Ors., 2009 (41) PTC 260 (Del) sets the tone as to what all needs to be provided to the patent office when a prospective patentee seeks grant of patent.” (para 32) “The submission advanced on behalf of the plaintiffs that the terminal disclaimer is an obviation and not an admission of obviousness is not an answer to the provisions of Section 8(2) of the Act which is mandatory. Assuming, under the USA patent law, it is construed as an obviation, even then, in my view, it was incumbent upon the plaintiffs to furnish the examination report of the USPTO. As to what would have followed from there, would obviously be within the ken of the examiner at the Indian Patent Office. The scope of Section 8 of the Act has been captured in Chemtura Corporation case.” In the passage extracted from Chemtura Corporation v Union of India (2009), the Court there had held that “As far as Section 8(2) is concerned, the Controller on his own may also require the applicant to furnish details” and that “That requirement is mandatory as has been further emphasised by the wording of Section 64(1) (j)”. (paras 32–32.3) The plaintiffs had contended “that the error, if any, was bona fide and, therefore, could not lead to revocation under Section 64(1)(m) of the Act.” (para 31.2) The Court held: “The reliance placed on behalf of the plaintiffs on a judgement of the Division Bench i.e. in Maj. (Retd.) Sukesh Behl case, in my view, misses a vital distinction between this case and the judgement rendered in Chemtura Corporation case. In this context, it is required to be noticed that the judgement in Maj. (Retd.) Sukesh Behl case was rendered in the context of Order XII Rule 6 of the Code of Civil Procedure, 1908 … whereas the judgement in Chemtura Corporation case was foregrounded in the provisions of Order XXXIX Rule 1 and 2 of the CPC” (“Code of Civil Procedure, 1908”) (para 32.4) “Construing these facts, the Court ruled that it was not a case of a clear and unambiguous admission, thus, triggering the provisions of Order XII Rule 6 of the CPC. Pertinently, the Court agreed with the judgement rendered in Chemtura Corporation case that the provisions of Section 8 were mandatory.” (paras 31–32.7)
10. Prosecution history abroad. “Before the USPTO, the plaintiffs filed a terminal disclaimer which, in sum, meant that the validity period of the corresponding US patent i.e. US 126 … and US 117 … would end on the same date.” (para 14) Of Quad Environment vs. Union Sanitary, Festo Corp. vs. Shoketsu Kinzoku and SimpleAir, Inc. vs. Google LLC, the Court held: “A perusal of these judgements would show that while terminal disclaimers are not treated as admissions, they are taken into account to ascertain the prosecution history of the patent i.e. the reason as to why the patentee chose to narrow down its claim. Thus, while terminal disclaimer filed by a patentee is not treated as a complete bar against the defence of non-obviousness, depending on facts, it can operate as estopped by conduct.” (paras 14, 32.8–32.9) “The point to be stressed here is that under our Act, was the examiner under the Indian Patent Office not entitled to know as to what was the prosecution history of the plaintiffs qua the corresponding patents in US. In my opinion, the answer to this has to be in the affirmative. Chemtura Corporation case, while interpreting the provisions of Section 8 of our Act, in a sense, in its own language, brings to fore this seminal point.” (para 33) “It, nevertheless, is an important factor to be taken into account at a preliminary injunction stage; at which point, the Court exercises equitable jurisdiction.” (paras 14, 32.8–33.1)
11. Credible challenge and balance of convenience. “In my view, if, as held by me above, the defendants have been able to set up a credible challenge and/or establish, at least at the preliminary injunction stage, the vulnerability of the suit patents, even if the balance of convenience is in favour of the plaintiffs, the injunction cannot be granted.” (para 34) “On the other hand, if the plaintiffs had established a strong prima facie case for grant of a preliminary injunction, they would still have to satisfy the Court as to whether or not balance of convenience was in their favour and that denial of interim relief would cause irreparable damage.” (paras 34–34.1)
12. Timing of the challenge. “The defendants, according to the plaintiffs, should be asked to ‘clear the way’ as contemplated in Merck Sharp and Dohme Corporation and Ors. vs. Glenmark Pharmaceuticals” (para 34.2). The Court held: “Having considered the case from the point of view of facets involving balance of convenience and irreparable harm, it has to be stated that the fact that a challenge has been laid at the stage when the plaintiffs seek to enforce their rights under the patents would not propel the Court … to grant an injunction if the challenge is credible.” (para 35) “Therefore, depriving the defendants, at this stage, from manufacturing and selling their drugs, when, during the validity period of the genus patent i.e. IN 147 they largely held themselves in check would, in my opinion, not be appropriate, especially, when they have set up a credible challenge to the suit patents.” (paras 34.2–35.4)
13. Grant and the quid pro quo. “The provisions of the Act do not provide any shield of inviolability. This principle is true not only in India but jurisdictions across the world. In no country, a mere grant of a patent by the patent offices’ guarantees their validity. It is important to remember that grant of monopoly to the inventor, which is necessary for her/him to recoup investments and/or derive profits from her/his inventions, comes with a quid pro quo as noticed in paragraph 38 of Report on the Revision of the Patents Law by Shri Justice N. Rajagopala Ayyangar (September, 1959).” The paragraph of the Report so extracted reads: “I have already set out the considerations which are said to constitute the quid pro quo for the grant of the patent monopoly, namely; (1) the working of the invention within the country so as to result in the establishment in the country of a new industry or an improvement of an existing industry which would profitably employ the labour and capital of the country and thus increase the national wealth, and (2) disclosure to the public of the invention and the manner of its working so that on the expiry of the life of the patent the public are enabled to work the invention themselves and in competition with each other.” (para 35.1)
14. Damages, price and the disease. “What persuades me to decline injunction, in addition to what I have stated above, is also the fact that in this case damages if proved at trial, appear to be compensable.” “The plaintiffs, however, for reasons best known to them have not placed on record the agreements arrived at with these entities in support of their plea. Therefore, it has to be inferred that the said entities are licensees.” (para 35.5) “Besides this, the plaintiffs also aver that they are importing their drug into the country. Therefore, the plaintiffs seek to monetize their invention. Thus, at the end of the trial, if they were to succeed, they could be granted damages, if proved, under the law. Thus, as long as a mechanism can be put in place for securing the recovery of damages by the plaintiffs, it would, at this stage, balance the interest of the parties.” (paras 35.5–35.6) “To my mind, this aspect can be quantitatively verified, to a large extent, if one were to compare the price of the drugs sold by the plaintiffs both, directly and/or indirectly, and the prices at which the defendants seek to offer their drugs.” (para 36.1) “Clearly the difference in prices of drugs ranges between 250% to 350%. Therefore, as is apparent, if defendants were allowed to manufacture and market their drugs, it would be far cheaper. Concerns as to quality, at this juncture, appear to be a self-serving argument. The concerned statutory authority can, in my view, adequately deal with this issue if and when such a situation arises.” (paras 36.1–36.2) “I may also indicate herein that an argument was raised that diabetes is a lifestyle disease and, therefore, the concerns generally expressed by Courts qua drugs which are used to treat life-threatening diseases such as Cancer, HIV/AIDS etcetera should not impact this matter.” (para 37) “The defendants on the other hand have emphasised that diabetes is no longer construed as a lifestyle disease.” (para 37.1) “On this aspect, judicial notice needs to be taken of the following figures published by the Government of India and World Health Organisation on diabetes.” The National Centre for Disease Control had noted that “India has 6.51 crore diabetes cases which is second highest number of diabetics in the world and is projected to have 10.9 crore affected persons by 2035.” (para 38) “Therefore, if one were to bear in mind the aspect concerning price as also the nature of the disease which is sought to be treated by the drug-in-issue, the scales of balance, in my opinion, at this stage, would weigh in favour of the defendants.” (paras 35.5–38.1)
15. Obiter. Double patenting. “Before I conclude … there is literature and scholarly articles available of well-established academicians which point in the direction that the doctrine of double patenting needs to be strengthened.” (para 39) “Some of the academicians appear to be of the view … that it must be presumed that the party with genus patent has invented the full scope of the genus. It is argued that when the same inventor holds a genus patent for a pharmaceutical product, such an inventor should be estopped from obtaining a species patent which is within the scope of genus, whether or not the genus patent constitutes prior art.” (paras 39–39.2)
16. Disposition. “Thus, for the foregoing reasons I am not inclined to grant an injunction in favour of the plaintiffs and against the defendants. Consequently, the captioned applications are dismissed.” (para 40) “The defendants will, however, via their respective affidavits, place on record the details, quantum, and value of drug manufactured and sold as also indirect and direct taxes paid in that behalf. This information will be placed on the Court’s record every quarter.” (para 41) “The defendants will also provide details of their assets … which would include their location and current market value. The information given in the affidavits will be backed by a certificate of a statutory auditor. The defendants via their affidavits will also undertake to pay damages as and when called upon to do so by the Court. These affidavits will be filed within a period of 3 weeks.” (para 41.1) “List the captioned matters on 15.01.2021.” (paras 40–42)

What the court did not decide

On anticipation by prior publication, the Court held that “while counsel for the defendants, based on the affidavit of Mr. Martin, did try to convey that a person skilled in the art could iterate the claims and arrive at 8 molecules based on prior publication and not hindsight, this is an aspect which would be required to be tested in a trial.” (para 28) On the plea of non-disclosure, it held that “as to whether or not the Court would, ultimately, revoke the suit patents for failure to furnish information, as sought for by the Indian Patent Office, would be ruled upon after the trial.” (para 33.1)

Subsequent treatment

• Appealed — AstraZeneca’s appeals from this judgment, FAO(OS)(COMM) 139/2020 and 140/2020, heard with seven connected appeals, were dismissed by a Division Bench of the Delhi High Court (Rajiv Sahai Endlaw and Amit Bansal JJ) on 20 July 2021 in AstraZeneca AB v Intas Pharmaceuticals Limited, 2021 SCC OnLine Del 3746, (2021) 87 PTC 374 (DB). The Division Bench held that “as held in the impugned judgment/order dated 2nd November, 2020, the question of the respondent(s)/defendant(s), by working DAPA” (“Dapagliflozin”) “, infringing IN 147 could arise only if DAPA was disclosed in IN 147” (para 43), and that “There is thus no merit in the appeals, which are dismissed, with costs assessed at Rs.5,00,000/- to the respondent(s)/defendant(s) in each of the suits” (para 52). On 19 July 2022 the Supreme Court, in SLP (C) 15650–15658/2021, held: “We are not inclined to interfere with such interim order in the present special leave petition. The trial will proceed uninfluenced by the findings recorded by the High Court.” It directed that “The costs imposed by the High Court shall abide the final Judgment and decree to be passed in the suits.”
• Followed — In Natco Pharma Limited v Novartis AG (Delhi High Court, Division Bench, 24 April 2024, FAO(OS)(COMM) 178/2021) the Division Bench set out para 18.3 of this judgment, recording that “the learned Single Judge rejected the contention that since the suit patents were old, they should be presumed to be valid” and that “the presumption of validity exists only till such time the patent is challenged and the challenge is credible” (para 44).
• Followed — In Boehringer Ingelheim Pharma GmbH & Co KG v Vee Excel Drugs and Pharmaceuticals Private Ltd, 2023:DHC:2265 (Delhi High Court, 29 March 2023), on the issue “Whether the validity of the suit patent has to be presumed on account of defendants not having filed pre-grant or post-grant opposition to the suit patent or having filed revocation petition belatedly?” (para 13), Amit Bansal J recorded that “Relying upon the judgment in Bishwanath Prasad (supra), Rajiv Shakdher, J. in AstraZeneca (supra) came to the conclusion that the challenge to the validity of the patent can be made at any stage and what is relevant is not the stage when the challenge is made, but the credibility of the challenge” (para 17). He recorded too that “the fact that the plaintiffs have filed an infringement suit for both the genus patent as well as the species patent, leads to a prima facie view that DAPA has been claimed in both the aforesaid patents” (para 40), and held that “the submission made on behalf of the plaintiffs that Linagliptin is not ‘covered’ or ‘disclosed’ in the genus patent is erroneous on the face of it” (para 50).