Can a sale by a third party 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, a sale by an independent third party can trigger the on-sale bar under 35 U.S.C. 102(b). The MPEP states:

A sale or offer for sale of the invention by an independent third party more than 1 year before the effective filing date of applicant’s claimed invention may be applied as prior art and may prevent applicant from obtaining a patent. (MPEP 2133.03(b))

However, there is an exception for patented methods that are kept secret and remain secret after a sale of the unpatented product of the method. In such cases, a sale by a third party does not trigger the on-sale bar, but a sale by the patentee or patent applicant would.

This interpretation highlights the importance of maintaining control over the invention and being cautious about disclosing it to third parties before filing a patent application, as even unknowing sales by others could potentially bar patentability.