What is the “Bayer” rule for determining public accessibility of printed publications?

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.

The “Bayer” rule, established in In re Bayer, 568 F.2d 1357, 196 USPQ 670 (CCPA 1978), is a guideline for determining public accessibility of printed publications. According to MPEP 2128:

“A reference will be considered publicly accessible if it was disseminated or otherwise made available to the extent that persons interested and ordinarily skilled in the subject matter or art, exercising reasonable diligence, can locate it.”

This rule emphasizes that public accessibility is not limited to wide distribution but includes any means by which interested persons could find the publication with reasonable effort.