the United States Government

“ Notwithstanding the preceding sentence, if a claim to a composition of matter is held invalid and that claim was the basis of a determination of nonobviousness under section 103 (b) (1) , the process shall no longer be considered nonobvious solely on the basis of section 103 (b) (1) . The burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity. ”

“ Section 282. Presumption of validity; defenses
A patent shall be presumed valid. Each claim of a patent (whether in independent, dependent, or multiple dependent form) shall be presumed valid independently of the validity of other claims; dependent or multiple dependent claims shall be presumed valid even though dependent upon an invalid claim. ”

“ The following shall be defenses in any action involving the validity or infringement of a patent and shall be pleaded:
(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 of this title as a condition for patentability, (3) Invalidity of the patent or any claim in suit for failure to comply with any requirement of sections 112 or 251 of this title, (4) Any other fact or act made a defense by this title. ”