What is double patenting?

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.

Double patenting is a judicial doctrine that prevents the unjustified extension of patent exclusivity beyond the term of a patent. There are two types of double patenting rejections:

• Statutory double patenting under 35 U.S.C. 101, which prohibits claiming the same invention twice
• Nonstatutory double patenting, which is based on a judicially created doctrine to prevent unjustified timewise extension of patent rights

As stated in MPEP 804: “The doctrine of double patenting seeks to prevent the unjustified extension of patent exclusivity beyond the term of a patent.”