New Delhi, Feb. 25 -- 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 pa...