Eris Lifesciences Limited v. Controller Of Patents & Anr.

In the high-stakes world of pharmaceuticals, patents are the lifeblood of innovation—and sometimes, the chains that bind competition. But what happens when a company believes a granted patent shouldn't have been granted in the first place? Is there a deadline to challenge it, or can the sword of revocation hang over a patentee's head indefinitely? This case answers that very question, and the answer reshapes how every founder and IP strategist should think about patent risk.

Macleods Pharmaceuticals Ltd, a major player in the pharmaceutical industry, found itself entangled in a patent dispute involving Respondent No.2, the patentee. The core of the conflict revolved around revocation petitions filed under Section 64 of the Patents Act. Respondent No.2, the patentee, sought to have these revocation petitions dismissed outright, arguing that they were time-barred—essentially claiming that Macleods had waited too long to challenge the patent's validity. The stage was set for a fundamental legal question: does the law impose a deadline on seeking revocation of a patent?

The patentee (Respondent No.2) argued that the revocation petitions should be thrown out because they were filed beyond any reasonable timeframe, essentially asserting a limitation defense. The implicit argument was that allowing challenges indefinitely would create uncertainty and undermine the granted patent's enforceability. Macleods, on the other hand, stood on the plain language of Section 64 of the Patents Act, which contains no explicit limitation period for filing revocation petitions. The legal friction centered on whether the court should read in a three-year limitation period (commonly applied in other civil matters) or whether the absence of a specific time bar meant revocation petitions could be filed at any time during the patent's life. Adding another layer, interim stay applications were also in play, with the patentee seeking to prevent any disruption to their already-granted patent rights.

The court ruled decisively in favor of the patentee. It held that since no specific limitation period is prescribed for revocation under Section 64 of the Patents Act, a three-year limitation period cannot be read into the provision. The court reinforced that revocation petitions are not bound by an arbitrary time clock—they can be filed whenever the interest arises or continues during the life of the patent. Furthermore, the interim stay applications were dismissed, recognizing that the patent had already been granted and that injunctions had been granted elsewhere in related proceedings. The outcome preserved the patentee's position and rejected the attempt to impose an external limitation period on Section 64.

For founders, startup leaders, and IP professionals, this case delivers a critical lesson: there is no statutory deadline for filing a patent revocation petition under Section 64 of the Patents Act. This means that as long as a patent is in force, it remains vulnerable to challenge at any time. For patent holders, this underscores the importance of building strong, defensible patents from day one—because the threat of revocation never truly expires. For challengers, it confirms that delay alone is not a bar to justice, but strategic timing remains crucial. Either way, patent validity is a living question, not a closed chapter.