Can experimental use negate 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.

While experimental use can potentially negate the on-sale bar, it becomes increasingly difficult to prove as commercial exploitation increases. The MPEP states:

“As the degree of commercial exploitation in public use or sale activity increases, the burden on an applicant to establish clear and convincing evidence of experimental activity with respect to a public use becomes more difficult.”

This means that inventors must be cautious when engaging in any commercial activities, even if they claim experimental purposes. The primary purpose of the activity must be genuinely experimental, not commercial. For instance, the Sunoco Partners case demonstrates that testing at a third-party location instead of the buyer’s facility, when it could have been done before the offer to sell, indicated that experimentation was not the primary purpose of the sale.