Boost for generics as Delhi High Court says expired patents can still be cancelled

India’s generic drugmakers will no longer automatically face damages claims linked to expired patents after the Delhi High Court ruled that even a patent that has completed its 20-year term can be cancelled if it is under legal challenge.

Delivering the first clear ruling on the issue under Indian patent law, a division bench of Justice C. Hari Shankar and Justice Om Prakash Shukla said on 24 February that the expiry of a patent does not prevent courts from examining its legal validity at the time of issurance. If such a patent is later revoked, it will be treated as if it never legally existed.

The dispute involves Boehringer Ingelheim, a German drugmaker, and Macleods Pharmaceuticals, which are fighting over a patent for the diabetes drug Linagliptin. Macleods challenged the patent’s validity in the Delhi High Court, while Boehringer filed an infringement suit in the Himachal Pradesh High Court, seeking an injunction and damages.

The German drugmaker argued that the cancellation case should be stopped because the patent had already expired and because its validity was already being questioned in another lawsuit. The court disagreed and rejected the plea. It said that even if a patent has expired, it can still be cancelled.

‘No clear precedent’

Importantly, the court observed that there is no clear Indian precedent directly dealing with whether a revocation petition can continue after a patent expires and whether such revocation operates retrospectively. In the absence of a binding Indian ruling on this issue, the bench relied on the UK Supreme Court’s decision.

Under patent law, a revocation plea is a legal request made to a court to cancel a patent that has already been granted. If the court allows it, the patent is removed and treated as if it was never valid.

Major ramifications

This ruling could have major consequences for damages in Indian pharma disputes. Indian generic drugmakers, which have mastered reverse engineering, often pursue patent challenges against innovators for life-saving or blockbuster drugs. Innovators, on the other hand, frequently file multiple patents for a single product to extend market exclusivity, a practice often described as ‘evergreening’.

In many high-stakes cases, innovator companies file infringement suits seeking compensation, while generics companies file revocation petitions challenging the patent. Even after a patent expires, the patent holder can still seek money for alleged infringement during its lifetime. However, if the patent is later cancelled, the legal basis for those damages may disappear.

Take for example Danish drugmaker Novo Nordisk and its blockbuster drug semaglutide, which is set to go off patent in India in March. Several Indian drugmakers such as Dr. Reddy’s Laboratories, Sun Pharmaceutical Industries, and Natco Pharma have filed patent challenges or non-infringement suits in a bid to launch their versions earlier and gain an advantage.

In most such cases, the patent expires before the matter is finally decided. Historically, generic companies could still be liable to pay damages to the innovator if the final ruling went against them after patent expiry.

‘Greater litigation risk for patent holders’

Legal experts said the latest judgment significantly raises litigation risk for patent holders, as revocation could impact past royalties and licensing arrangements. The decision is expected to encourage generics to file more revocation petitions and adopt a more aggressive strategy, while forcing innovator companies to defend patent validity more carefully in high-stakes disputes.

“We can expect generic companies to be more aggressive in filing revocation petitions, knowing that the benefits extend beyond freedom to operate — they also neutralize damages exposure,” said Essenese Obhan, managing partner at Obhan Mason.

According to Himanshu Deora, partner at King Stubb & Kasiva, the ruling is likely to change how pharma patent cases are fought. Generics may adopt a dual strategy of challenging both infringement and validity simultaneously. Innovator companies, in turn, may need to assess patent strength more carefully before filing lawsuits and be cautious while seeking damages. Patent validity, he said, will become even more central to enforcement strategy.

Once a patent expires or is revoked, drug prices can fall sharply. In the case of life-saving drugs, this can be a major win for patients. For instance, Zydus Lifesciences launched a generic version of nivolumab at a significantly lower price compared to innovator Bristol-Myers Squibb after court clearance. Similarly, Natco Pharma launched a generic version of risdiplam at a fraction of the price charged by Roche.

In blockbuster segments such as weight loss, generics are vying for an early-mover advantage to capture a larger share of the market. Innovator brands such as Mounjaro, Wegovy and Ozempic have already crossed ₹1,000 crore in sales within a year of launch. Analysts estimate the market could grow to ₹2,000-3,000 crore by FY27 once patents expire.