Challengers may bring an action in district court seeking a declaratory judgment on invalidity. Alleged infringers often bring counter-claims seeking declaratory judgment that asserted patents are invalid or unenforceable. Challengers may also seek a ruling on invalidity from the PTO by filing a request for a Post-Grant review. This section focuses on actions in District Court. However, much of the material presented here applies equally to PTAB reviews.
A patent is presumed valid from the time it issues. Each claim of a patent is presumed valid independent of the validity of other claims.
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 burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity.
— 35 U.S. Code § 282 (a).
The party that brings a validity challenge bears the burden to prove invalidity.
A patent is presumed valid, and the burden of establishing invalidity as to any claim of a patent rests upon the party asserting such invalidity. 35 U.S.C. § 282 (1982). The presumption of validity is a procedural device that mandates that the party asserting invalidity bears the initial burden of establishing a prima facie case of obviousness under 35 U.S.C. § 103.
— Ashland Oil, Inc. v. Delta Resins & Refractories, 776 F. 2d 281, 291 (Fed. Cir. 1985).
A challenger must establish invalidity by clear and convincing evidence.
Under § 282 of the Patent Act of 1952, "[a] patent shall be presumed valid" and "[t]he burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity." 35 U.S.C. § 282. We consider whether § 282 requires an invalidity defense to be proved by clear and convincing evidence. We hold that it does.
— Microsoft Corp. v. i4i Ltd. Partnership, 131 S. Ct. 2238, 2242 (S. Ct. 2011).
The requirements for patentability must exist ex-ante, at the time a patent application is submitted and findings must reflect the risks posed by hindsight bias.
A factfinder should be aware, of course, of the distortion caused by hindsight bias and must be cautious of arguments reliant upon ex post reasoning.
— KSR Intern. Co. v. Teleflex Inc., 127 S. Ct. 1727, 1742 (S. Ct. 2007).