On September 16, 2011, the America Invents Act (AIA) ushered in major changes to the U.S. patent system, including changes to available defenses for patent infringement. One provision that took place immediately on enactment amended 35 U.S.C. § 282 to remove the failure to disclose the best mode – required to obtain a patent under 35 U.S.C. § 112 – as a means to invalidate or cancel an issued patent.

In relevant part, 35 U.S.C. § 282 now enumerates the defenses available in any action involving validity or infringement of a patent as:

(1) Noninfringement, absence of liability for infringement or unenforceability,

(2) Invalidity of the patent or any claim in suit on any ground specified in part II as a condition for patentability...