What are the four requirements imposed by 35 U.S.C. 101?

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.

35 U.S.C. 101 imposes four main requirements for patent eligibility:

1. The invention must fall within one of the four statutory categories: process, machine, manufacture, or composition of matter.
2. The invention must be directed to patent-eligible subject matter and not a judicial exception (unless it includes additional limitations amounting to significantly more than the exception).
3. Only one patent can be issued for the same invention to the same inventor or inventive entity.
4. The invention must have a specific, substantial, and credible utility.

As stated in the MPEP: “35 U.S.C. 101 has been interpreted as imposing four requirements.” These requirements form the foundation for determining patent eligibility under U.S. patent law.