How are non-written disclosures treated as prior art in international patent applications?

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.

Non-written disclosures, such as oral disclosures, use, or exhibitions, are addressed in MPEP 1878.01(a) and PCT Rule 64.2. These disclosures are generally not considered part of the prior art if:

1. The non-written disclosure occurred before the relevant date
2. The date of the non-written disclosure is indicated in a written disclosure
3. The written disclosure was made available to the public on or after the relevant date

However, the MPEP notes: “Nevertheless, the international preliminary examination report shall call attention to such non-written disclosure in the manner provided for in Rule 70.9.”

This means that while non-written disclosures may not be used to challenge novelty or inventive step, they should still be mentioned in the examination report.