35 U.S.C. § 282 : US Code - Section 282: Presumption of validity; defenses

Search 35 U.S.C. § 282 : US Code - 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. 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.
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.
In actions involving the validity or infringement of a patent the
party asserting invalidity or noninfringement shall give notice in
the pleadings or otherwise in writing to the adverse party at least
thirty days before the trial, of the country, number, date, and
name of the patentee of any patent, the title, date, and page
numbers of any publication to be relied upon as anticipation of the
patent in suit or, except in actions in the United States Court of
Federal Claims, as showing the state of the art, and the name and
address of any person who may be relied upon as the prior inventor
or as having prior knowledge of or as having previously used or
offered for sale the invention of the patent in suit. In the
absence of such notice proof of the said matters may not be made at
the trial except on such terms as the court requires. Invalidity of
the extension of a patent term or any portion thereof under section
154(b) or 156 of this title because of the material failure -
(1) by the applicant for the extension, or
(2) by the Director,
to comply with the requirements of such section shall be a defense
in any action involving the infringement of a patent during the
period of the extension of its term and shall be pleaded. A due
diligence determination under section 156(d)(2) is not subject to
review in such an action.