Pfaff v. Wells Electronics, Inc.
United States Supreme Court
525 U.S. 55 (1998)
Pfaff (plaintiff) entered a written agreement to sell a computer component to Texas Instruments more than a year before his patent-filing date, having only sketches and no prototype; the design was manufactured for the first time months later, still within the one-year window before filing. Pfaff sued Wells (defendant) for infringement; the district court held the one-year on-sale bar could not apply because the invention had not yet been reduced to practice when offered for sale, but the court of appeals reversed, finding the invention "substantially complete" at the time of the offer.
Whether an invention that has not yet been reduced to practice, but which the inventor has begun to commercially market, is "on sale" under the patent statute's one-year bar.