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

Question

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?

Answer 1

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.

Answer 2

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

Answer 3

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.

http://www.youtube.com/watch?v=CUjsCv8khdQ