If a patent has been issued, can it still be invalidated by prior art?



Assuming the invention disclosed in a patent issued by the USPTO has been described in a book two years before it was submitted, can this patent still be invalidated by this prior art? If yes what is the procedure to follow?

Jérôme Verstrynge

Posted 2012-10-01T15:54:36.903

Reputation: 367



Yes. An issued patent is presumed to be valid, but a challenger can produce prior art to demonstrate that the claims of the patent were anticipated or rendered obvious.

There are administrative post-grant procedures for challenging an issued patent, and, of course, anyone who is sued by a patent holder can support a defense of invalidity by producing prior art - even possibly art that was originally considered by the Patent Office when the patent was issued.


Posted 2012-10-01T15:54:36.903

Reputation: 1 718


There is some information related to the post-grant review process here: http://patents.stackexchange.com/questions/528/what-is-the-time-period-allowed-to-get-a-post-grant-review

– Robert Cartaino – 2012-10-01T18:54:53.133


I have also posted a comment that discusses mechanisms for challenging patent rights here: http://patents.stackexchange.com/questions/590/over-time-which-patent-legislation-applies-current-or-past

– Dennis Crouch – 2012-10-01T20:00:53.630


That said, the America Invents Act does create a new avenue for challenging patents, albeit a limited one. It allows third parties to introduce evidence of so-called “prior art” (proof the invention had already been invented) to block patents from being issued, and it also introduces a new framework to challenge patents in a “post-grant review” process.

Source: http://www.wired.com/threatlevel/2011/09/obama-signs-patent-reform-bill-crustless-sandwich-still-patented

Elijah Lynn

Posted 2012-10-01T15:54:36.903

Reputation: 183

There is a good description of the various post-grant proceedings, like PGR, IPR, CBM etc. here http://fishpostgrant.com/inter-partes-review/

– None – 2014-06-05T05:56:51.800


Here is a video of Tim Meyer explaining post-grant proceedings as of 2009. This is before the "new framework to challenge patents in a "post-grant review" process" so keep that in mind when watching it.


Elijah Lynn

Posted 2012-10-01T15:54:36.903

Reputation: 183