What were Defensive Publications in the patent system?

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.

Defensive Publications were a type of USPTO publication for provisionally abandoned patent applications. According to MPEP 901.06(d):

“Defensive Publications (the O.G. defensive publication and search copy) are U.S. Patent and Trademark Office publications of provisionally abandoned applications wherein the applicant retains their rights to an interference for a limited time period of 5 years from the earliest effective U.S. filing date.”

Defensive Publications allowed inventors to disclose their inventions publicly while retaining certain rights for a limited period. This system was replaced by Statutory Invention Registrations in 1985.