Revocation

A patent can be cancelled years after it was granted, and the most common place that happens is in the middle of a case the patentee started.

In simple words

Cancellation of a granted patent by a High Court, on a petition by a person interested or the Central Government, or by way of a counterclaim in an infringement suit.

Think of it as

Undoing the grant.

Why it matters

The grounds are wide - lack of novelty, obviousness, non-patentable subject matter, insufficiency, wrongful obtaining, failure to disclose foreign filing particulars, and more. Because grant carries no warranty of validity, a defendant will almost always counterclaim for revocation.

A simple example

A patentee sues. The defendant counterclaims for revocation citing two documents the examiner never found. The patentee is now defending validity as well as asserting infringement.

Common mistake

Choosing both routes at once. A party generally has to elect between a revocation petition and a counterclaim rather than pursuing both on the same patent.

Where it comes from

Patents Act 1970 - section 64; and section 13(4), which states that grant does not warrant validity