## Facts

- Wayne K. Pfaff developed a computer chip socket design at the request of Texas Instruments (TI) in late 1980.
- By February or March 1981, Pfaff prepared detailed engineering drawings specifying the socket’s design, dimensions, and materials, and sent them to a manufacturer to begin production.
- Before March 17, 1981, Pfaff showed TI a sketch of the concept.
- On April 8, 1981, TI sent written confirmation of an earlier oral purchase order for 30,100 sockets for $91,155.
- At the time of the TI order, no prototype had been built; Pfaff’s practice was to offer products commercially without first building and testing a prototype.
- Tooling took months; Pfaff first filled the TI order in July 1981, indicating first reduction to practice occurred in summer 1981.
- Pfaff filed his patent application on April 19, 1982, making April 19, 1981 the § 102(b) one-year “critical date.”
- After the patent issued, Pfaff sued Wells Electronics for infringement; Wells asserted invalidity under the § 102(b) on-sale bar.

## Issues

1. Whether an invention is “on sale” under 35 U.S.C. § 102(b) when it is the subject of a commercial offer for sale more than one year before the patent application, even if it has not yet been reduced to practice.
2. What standard governs whether the invention was sufficiently complete at the time of the commercial offer to trigger the § 102(b) on-sale bar.

## Decision

- The Supreme Court unanimously affirmed the Federal Circuit.
- The Court held the patent invalid because the invention was on sale in the United States more than one year before the application was filed.
- The Court adopted a two-part test for the § 102(b) on-sale bar: (1) a commercial offer for sale, and (2) the invention was ready for patenting at the time of the offer.
- The TI purchase order constituted a commercial offer for sale before the critical date.
- The invention was ready for patenting before the critical date because Pfaff’s drawings and descriptions were sufficiently specific to enable a skilled person to make the invention, even though no prototype existed.

## Legal Principles

- The § 102(b) on-sale bar does not require actual reduction to practice before the one-year period begins to run.
- An invention is “on sale” under § 102(b) if, before the critical date:  
  - it is the subject of a commercial offer for sale; and  
  - it is ready for patenting, shown by either (a) reduction to practice, or (b) enabling drawings or other descriptions sufficient for a skilled person to practice the invention.
- “Invention” for these purposes centers on the inventor’s conception; a physical embodiment is not necessary if the invention is otherwise enabled for patenting.
- Section 102(b) limits how long an inventor may commercially exploit an invention before filing, preventing extension of exclusivity through pre-filing commercialization.

## Conclusion

The Court held that Pfaff’s pre-critical-date sale activity triggered the § 102(b) on-sale bar because TI received a commercial offer for the sockets and the invention was ready for patenting based on enabling drawings, rendering the patent invalid.


Pfaff v. Wells Elecs., Inc., 525 U.S. 55 (1998)