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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?

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up vote 9 down vote accepted

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.

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There is some information related to the post-grant review process here:… – Robert Cartaino Oct 1 '12 at 18:54
I have also posted a comment that discusses mechanisms for challenging patent rights here:… – Dennis Crouch Oct 1 '12 at 20:00

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.


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There is a good description of the various post-grant proceedings, like PGR, IPR, CBM etc. here – user8771 Jun 5 '14 at 5:56

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.

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