Nor can that of other interested witnesses. E.g., Lacks Indus., Inc. v. McKechnie Vehicle Components USA, Inc., 322 F.3d 1335, 1350 (Fed. Cir. 2003). Instead, "an alleged co-inventor must supply evidence to corroborate his testimony."

The determination that a product was placed "on sale" under 35 U.S.C. § 102(b) "is a conclusion of law based on underlying findings of fact." Lacks Industries, Inc. v. McKechnie Vehicle Components USA, Inc., 322 F.3d 1335, 1347 (Fed. Cir. 2003). Pursuant to 35 U.S.C. § 282 there is a statutory presumption of validity that requires each claim of a patent to be presumed valid.

On appeal and cross-appeal to this court, we affirmed the finding of infringement but vacated the invalidity decision. Lacks Indus., Inc. v. McKechnie Vehicle Components USA, Inc., 322 F.3d 1335 (Fed. Cir. 2003). We concluded that the Special Master erred by applying an outdated legal standard that was superseded by Group One, Ltd. v. Hallmark Cards, 254 F.3d 1041, 1048 (Fed. Cir. 2001), a decision handed down after the Special Master issued his findings and conclusions.

We pause to note that the law generally requires that oral testimony of invalidity must be corroborated. SeeLacks Industries, Inc. v. McKechnie Vehicle Components USA. Inc., 322 F.3d 1335, 1350 (Fed. Cir. 2003) ("A review of the relevant case law reveals a clear requirement that such oral testimony by interested parties must be corroborated by documentary testimony"); Finnigan Corp. v. International Trade Comm'n, 180 F.3d 1354, 1366 (Fed. Cir. 1999) ("The law has long looked with disfavor upon invalidating patents on the basis of mere testimonial evidence absent other evidence that corroborates that testimony"); Woodland Trust v. Flowertree Nursery. Inc., 148 F.3d 1368, 1371 (Fed. Cir. 1998) ("Corroboration of oral evidence of prior invention is the general rule in patent disputes"). The need for corroboration holds true regardless of whether the party testifying is interested in the outcome of the litigation or is uninterested, but testifying on behalf of an interested party.Finnigan Corp., 180 F.3d at 1367.

A literal infringement analysis requires two separate steps. Lacks Industries, Inc. v. McKechnie Vehicle Components USA, Inc., 322 F.3d 1335, 1341 (Fed. Cir. 2003); Southwall Technologies, Inc. v. Cardinal IG Co., 54 F.3d 1570, 1575 (Fed. Cir. 1995). First, the asserted claims must be interpreted by the court as a matter of law to determine their meaning and scope.

For many years this court applied a “totality of circumstances” standard in applying the on-sale bar. Lacks Indus. v. McKechnie Vehicle Components USA, Inc. , 322 F.3d 1335, 1347 (Fed. Cir. 2003) (citing Envirotech Corp. v. Westech Eng'g Inc. , 904 F.2d 1571, 1574 (Fed. Cir. 1990) ). “Under that test ‘no single finding or conclusion of law [was] a sine qua non’ to a holding that the statutory bar arose.” Id.

“Our patent laws deny a patent to an inventor who applies for a patent more than one year after making an attempt to profit from his invention by putting it on sale.” Atlanta Attachment Co. v. Leggett & Platt, Inc., 516 F.3d 1361, 1365 (Fed.Cir.2008) ; see City of Elizabeth v. Am. Nicholson Pavement Co., 97 U.S. 126, 137, 24 L.Ed. 1000 (1877) (“[A]n inventor acquires an undue advantage over the public by delaying to take out a patent, inasmuch as he thereby preserves the monopoly to himself for a longer period than is allowed by the policy of the law.”). Section 102(b)'s on-sale bar is triggered when a claimed invention is: (1) ready for patenting; and (2) the subject of a commercial offer for sale prior to the critical date.Pfaff v. Wells Elecs., Inc., 525 U.S. 55, 67–68, 119 S.Ct. 304, 142 L.Ed.2d 261 (1998) ; see Lacks Indus., Inc. v. McKechnie Vehicle Components USA, Inc., 322 F.3d 1335, 1347 (Fed.Cir.2003). “The date exactly one year prior to the date of application for the patent is known as the critical date.”

As this court has repeatedly stated, a commercial offer for sale under § 102(b) is “one which the other party could make into a binding contract by simple acceptance.” Grp. One Ltd., 254 F.3d at 1048;see also Lacks Indus., Inc. v. McKechnie Vehicle Components, USA, Inc., 322 F.3d 1335, 1348 (Fed.Cir.2003); Dana Corp. v. Am. Axle & Mfg., Inc., 279 F.3d 1372, 1377 (Fed.Cir.2002). Hamilton Beach takes aim at the district court's reliance on the supplier's response email requesting a “release” before it could begin production of the slow cookers.

As this court has repeatedly stated, a commercial offer for sale under § 102(b) is "one which the other party could make into a binding contract by simple acceptance." Grp. One Ltd., 254 F.3d at 1048; see also Lacks Indus., Inc. v. McKechnie Vehicle Components, USA, Inc., 322 F.3d 1335, 1348 (Fed. Cir. 2003); Dana Corp. v. Am. Axle & Mfg., Inc., 279 F.3d 1372, 1377 (Fed. Cir. 2002). Hamilton Beach takes aim at the district court's reliance on the supplier's response email requesting a "release" before it could begin production of the slow cookers.

Nor can that of other interested witnesses. E.g., Lacks Indus., Inc. v. McKechnie Vehicle Components USA, Inc., 322 F.3d 1335, 1350 (Fed. Cir. 2003). Instead, “an alleged co-inventor must supply evidence to corroborate his testimony.