MPEP 2100: Patentability

Answer in brief

MPEP Chapter 2100 covers patentability: subject-matter eligibility, novelty, obviousness, and the written description and enablement requirements. It is the most heavily tested chapter on the patent bar, at roughly 30–35% of questions by Wysebridge's estimate.

What it covers

Subject-matter eligibility under 35 U.S.C. 101 (MPEP 2106).
Novelty and prior art under 35 U.S.C. 102, pre-AIA and AIA (2131–2159).
Obviousness under 35 U.S.C. 103, including the KSR rationales (2141–2145).
Claim definiteness, written description and enablement under 35 U.S.C. 112 (2161 onward).

Read it

MPEP 2100 in full, free in Wysebridge's MPEP Center, or at the USPTO.

Questions & answers

What is MPEP 2143?

Examples of the rationales that support a conclusion of obviousness under 35 U.S.C. 103, following the Supreme Court's KSR decision. Read MPEP 2143.

Sources for this entry

Manual of Patent Examining Procedure (MPEP) USPTO
The examination manual the patent bar is tested on; open book during the exam.
Wysebridge MPEP Center Wysebridge (publisher of this site)
The full MPEP (9th Ed., Rev. 01.2024) free to read, with Wysebridge's estimated patent bar weight for each chapter.

Practical guidance is original editorial content. Company-published figures are the company's own claims and are labeled as such.

Continue this reading path

MPEP 700: Examination of Applications MPEP chapters Using the MPEP on the patent bar

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This is one of a coordinated collection of Wysebridge references. The related sites answer neighboring questions and share the same publisher entity, Wysebridge. They are not independent endorsements.

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MPEP.net. “MPEP 2100: Patentability.” Wysebridge Reference. Content reviewed 9 November 2026.
https://mpep.net/mpep-2100-patentability/