Ultra Flex offered to sell the product to Gerber.

Gerber understood that its initial orders would need to be ordinary display bags with holes because the bags with chip hooks would require the development of a special mold before they could be produced in quantity. The bags with chip hooks were not ultimately shipped until after the critical date; thus, although they were conceived before the critical date, the parties dispute whether they were indeed ready for patenting when Ultra Flex made the offer.

The Supreme Court ruling in Pfaff v. Wells Electronics, Inc., 525 U.S. 55 (1998) held a two-prong test for determining on-sale bar: dates of conception, and reduction to practice. PolyPro Flex had demonstrated conception before the critical date, but carried the burden of showing reduction to practice, so as to maintain its charge of invalidity.

Polypro has the burden to show by clear and convincing evidence that the bags were ready for patenting before the critical date. See Enzo Biochem, Inc. v. Gen-Probe, Inc., 424 F.3d 1276, 1281 (Fed. Cir. 2005). It can accomplish this “in at least two ways: by proof of reduction to practice before the critical date; or by proof that prior to the critical date the inventor had prepared drawings or other descriptions of the invention that were sufficiently specific to enable a person skilled in the art to practice the invention.” Pfaff, 525 U.S. at 67–68. At summary judgment, we must view the evidence in the light most favorable to Ultra Flex, see Enzo Biochem, 424 F.3d at 1281, and determine de novo whether the evidence “show[s] that there is no genuine issue as to any material fact,” see Fed. R. Civ. P. 56(c). We conclude that Polypro has failed to carry its burden.

PolyPro had a problem documenting the date of reduction to practice.

Polypro is correct that the inquiry is whether any bag, even a prototype, existed as of the critical date, not whether Ultra Flex had fully developed a method for mass-producing the patented bags, but it has failed to demonstrate the absence of a genuine issue of material fact as to when the patented bags first existed at all.

With a question of fact lingering, summary judgment was inappropriate.

We decline to express a view as to whether a reasonable jury could find in Polypro’s favor on the basis of the evidence that Polypro presented in support of its motion; we merely hold that a reasonable jury could find in favor of Ultra Flex on the basis of that evidence, thus precluding a grant of summary judgment to Polypro. We also note that on remand, the district court should consider the merits of Polypro’s alternative arguments, previously deemed moot, that the patents at issue are unenforceable due to inequitable conduct.

Summary judgment reversed, and remanded.