Revocation petition maintainable though no live patent subsisting: Macleods Pharmaceuticals Ltd v. Boehringer Ingelheim Pharma

Macleods Pharmaceuticals Ltd., the petitioner, is engaged in manufacturing and marketing diverse pharmaceutical products, including anti-diabetic drugs. The respondent, Boehringer Ingelheim Pharma GmbH & Co. KG, is a company organized under the laws of Germany and is involved in developing, manufacturing, and marketing pharmaceuticals worldwide, including India.

The dispute centers around a medicinal product called Linagliptin, an anti-diabetic product for which the respondent holds an Indian Patent IN 2433013. The patent was granted on October 5, 2022, with a priority date of August 21, 2023. The petitioner filed a revocation petition under Section 64(1) of the Patents Act (1970) at the Delhi High Court, seeking to revoke this patent. This petition was filed on February 17, 2022, just before the intended commercial launch of the petitioner’s generic Linagliptin product on February 22, 2022.

On February 19, 2022, the respondent filed an infringement suit against the petitioner before the High Court of Himachal Pradesh, alleging infringement of the subject patent. The term of the subject patent expired on August 18, 2023.

Petitioner’s contentions

• Difference in legal consequences: The petitioner argued that the defense under Section 107 of the Patents Act in an infringement suit has different legal and practical consequences from a revocation petition under Section 64. Section 107 does not entitle a defendant to seek revocation but only to seek a declaration that one or more claims are invalid. In contrast, a revocation petition can result in the entire patent being removed from the Register of Patents.
• Independent right to file revocation petition: The petitioner contended that under the scheme of the Patents Act, Section 64 provides a stand-alone right to file a revocation petition, whether a suit has been filed or not. There is no time limit prescribed for availing rights under Section 64, and it can be exercised at any point in time, independent of whether the patent subsists or has expired.
• Survival of cause of action: The petitioner argued that a patentee could file a suit for infringement, claiming damages even after the expiry of the patent. Therefore, the cause of action to file a revocation petition after the expiry of the patent shall also survive.
• Effect of revocation petition: The petitioner emphasized that a revocation petition is of the entire patent, and if allowed, the patent will be removed from the Register of Patents as if it never existed. This is different from the defense of invalidity under Section 107, which can be raised by individual claims asserted in the suit.

Respondent’s contentions  

• Defense of invalidity already taken: The respondent argued that the petitioner had already taken a defense of invalidity under Section 107 of the Patents Act in the written statement filed in the Himachal suit. The respondent contended that the prayers sought in the present petition and those made in the written statement (in the Himachal suit) were similar, which could result in conflicting judgments from two High Courts.
• No difference in the finding of invalidity: The respondent claimed that there is no difference between a finding of invalidity returned in an infringement suit/counter-claim or a revocation petition. A finding of invalidity would be binding on the patentee, and the patent could no longer be enforced, irrespective of whether the revocation petition had been filed or not.
• Comprehensive proceeding in infringement suit: The respondent argued that the infringement suit would constitute a more comprehensive proceeding with respect to the existing disputes between the parties as evidence would be led on behalf of the parties. Therefore, the adjudication of the present petition would be an exercise in futility.
• No live patent subsisting: The respondent contended that as there was no live patent subsisting in the Register of Patents, the petitioner no longer qualified as a ‘person interested‘ in terms of Section 2(1)(t) of the Patents Act. They relied on the case of Dr Reddy’s Laboratories Limited and Anr. v. Controller of Patents and Ors., 2022 SCC OnLine Del 10404. However, the court took the view that: “The issue before the court in the said judgment was whether the revocation petition was barred by limitation. It was held that under Section 64 of the Patents Act, there is no limitation, which is prescribed and, therefore, no limitation can be read into it. The observations with regard to the revocation petition being filed during the term of the patent were in the nature of obiter and, therefore, no reliance can be placed on the same.”

Delhi High Court decision

The court analyzed Section 64 of the Patents Act, which allows a patent to be revoked on a petition filed by a ‘person interested‘ or the Central Government. The term ‘person interested‘ is defined under Section 2(1)(t) of the Patents Act and includes a person engaged in or promoting research in the same field as that to which the invention relates. The court ruled that the petitioner is a person interested in the manufacture and sale of the patented products and is also a defendant in the patent infringement suit filed by the respondent. Therefore, the petitioner qualifies as a ‘person interested‘ and is entitled to file and maintain the revocation petition.

The court also noted that the respondent had filed a patent infringement suit claiming damages for the alleged infringement of its patent during the life of the patent. The court reasoned that just because the term of the patent has expired, it does not mean that the suit has become infructuous, as the cause of action for damages still survives. Applying the same rationale, the court concluded that a revocation petition can be filed or sustained even after the term of the patent has expired.

The court emphasized that the Himachal suit filed by the respondent is continuing despite the term of the patent having expired. If the petitioner wins the revocation petition and the patent is revoked, the respondent’s suit will be dismissed. Therefore, there is a valid cause of action for the petitioner to pursue the revocation petition, and the expiry of the patent does not render the petition infructuous. Consequently, the court dismissed the applications filed by the respondent seeking dismissal of the revocation petition.

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