Can a single sale or offer to sell trigger the on-sale bar?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

Yes, even a single sale or offer to sell can trigger the on-sale bar under 35 U.S.C. 102(b). The MPEP explicitly states:

Even a single sale or offer to sell the invention may bar patentability under pre-AIA 35 U.S.C. 102(b). (MPEP 2133.03(b))

This principle is supported by case law, including Consolidated Fruit-Jar Co. v. Wright and Atlantic Thermoplastics Co. v. Faytex Corp. It’s important for inventors and patent applicants to be aware that even a single commercial transaction involving the invention can potentially bar patentability if it occurs more than one year before the patent application filing date.