Understanding the Legal Battle Over LINAGLIPTIN: A Case Study on Patent

Introduction

The recent legal battle between Macleods Pharmaceuticals Ltd. (hereinafter ‘the Petitioner’) and Boehringer Ingelheim Pharma GmbH & Co. KG (hereinafter ‘the Respondent’) over the anti-diabetic drug LINAGLIPTIN has brought to light important aspects of patent law in India. The case primarily revolves around the revocation of Indian Patent No. IN 243301 (hereinafter IN’301), owned by the Respondent, and the legal question of whether a patent can be challenged even after its expiry.

Background of the Case

1. Who are the parties involved?

• Macleods Pharmaceuticals Ltd. (the Petitioner): An Indian pharmaceutical company involved in the manufacturing and marketing of diverse pharmaceutical products, including anti-diabetic drugs.

• Boehringer Ingelheim Pharma GmbH & Co. KG (the Respondent): A German pharmaceutical giant that owns the patent for LINAGLIPTIN, a widely used anti-diabetic drug.

2. What is the dispute about?

• The Respondent was granted Patent No. IN’301 on 5th October 2022 for LINAGLIPTIN, which was set to expire on 18th August 2023.

• Before the expiry of the patent, the Petitioner planned to launch a generic version of LINAGLIPTIN.

• To avoid any legal issues, the Petitioner filed a revocation petition under Section 64(1) of The Patents Act, 1970 (hereinafter ‘the Act’) on 17th February 2022, seeking to invalidate the patent.

• In response, the Respondent filed an infringement suit against the Petitioner in the Hon’ble High Court of Himachal Pradesh.

• The key legal questions adjudicated in I.A. 7635/2024 and I.A. 46685/2024 were:

  1. Whether a revocation petition maintainable if the petitioner has already raised an invalidity defence under Section 107 of the Act in an infringement suit?

  2. Whether a revocation petition can be filed or sustained after the expiry of the term of the patent?

Key Legal Issues and the Hon’ble Court's Findings

1. Maintainability of the Revocation Petition Despite an Invalidity Defence in the Infringement Suit

Respondent’s Argument:

• The Respondent argued that the Petitioner had already taken an invalidity defence under Section 107 of the Act in the infringement suit pending before the Hon’ble High Court of Himachal Pradesh.

• They claimed that the two parallel proceedings could lead to conflicting judgments, and hence, the revocation petition should be dismissed.

• The infringement suit was considered more comprehensive, making the revocation petition unnecessary.

Petitioner’s Argument:

• A revocation petition under Section 64 of the Act is an independent and broader remedy, whereas Section 107 of the Act only provides a defence against infringement claims.

• A revocation order applies universally and removes the patent from the register (in rem), while an invalidity defence in an infringement suit only affects the parties involved (in persona).

• Section 151 of the Act explicitly recognizes that revocation decisions and infringement suit findings serve different legal purposes. Therefore, the effect of the two proceedings is completely different.

The Hon’ble Court’s Decision:

• The Hon’ble Court upheld the maintainability of the revocation petition, clarifying that revocation under Section 64 of the Act and invalidity defence under Section 107 of the Act are distinct remedies.

• There is no legal requirement to file a counterclaim for revocation in an infringement suit instead of a standalone petition.

2. Can a Revocation Petition Be Filed or Sustained After the Expiry of the Patent?

Respondent’s Argument:

• Since the patent expired on 18th August 2023, the Petitioner no longer qualified as a “person interested” under Section 2(1)(t) of the Act.

• The Learned Council of the Respondent cited Dr. Reddy’s Laboratories Ltd. v. Controller of Patents, 2022 SCC OnLine Del 1040, arguing that revocation petitions should only be filed during the term of the patent.

Petitioner’s Argument:

• The Petitioner was still facing an infringement suit, meaning it had a continuing legal interest.

• The Act does not prescribe any time limit for filing a revocation petition.

• A patentee can still claim damages post-expiry, so the alleged infringer should be able to challenge validity post-expiry as well.

The Hon’ble Court’s Decision:

• The Hon’ble Court ruled that revocation petitions can be filed even after patent expiry if an infringement suit is still ongoing.

• Since the Respondent’s infringement suit was still active, the Petitioner had a valid cause of action to continue the revocation petition.

Final Ruling

• The revocation petition is maintainable, even though the Petitioner raised an invalidity defence in the infringement suit.

• Revocation petitions can be filed or sustained even after the patent has expired, provided there is a pending infringement suit or another legal interest.

• Revocation under Section 64 of the Act is distinct from an invalidity defence under Section 107 of the Act, with broader legal consequences.

Key Takeaways from the Case

• Revocation vs. Invalidity Defence:

• Revocation under Section 64 of the Act removes the patent from the register (in rem).

• Invalidity under Section 107 of the Act applies only between the parties in the infringement suit (in personam).

• Patent expiry does not make a revocation petition irrelevant:

• If a patentee can claim damages post-expiry, an infringer should still have the right to revoke the patent.

• Parallel legal proceedings are permissible:

• A defendant in an infringement suit can still file a separate revocation petition rather than just raising an invalidity defence.

Conclusion:

The case of Macleods Pharmaceuticals Ltd. (the Petitioner) v. The Controller of Patents & Anr. (C.O.(COMM.IPD-PAT) 38/2022) clarifies the scope of revocation petitions and invalidity defences in Indian patent law. It affirms that:

1. Revocation petitions are legally distinct from infringement defences and remain valid even when an invalidity defence is raised elsewhere.

2. Patent expiry does not prevent a revocation petition as long as the alleged infringer still has a legal stake in the matter.

This ruling is an important precedent for generic pharmaceutical companies, reinforcing their rights to challenge questionable patents and ensuring fair competition in the pharmaceutical industry.