35 U.S.C. · Part II · Chapter 10, Patentability of inventions

35 U.S.C. 101: Inventions patentable

In plain English

Section 101 says what kind of thing can be patented: a new and useful process, machine, manufacture or composition of matter, or a new and useful improvement of one. Almost every invention falls into one of the four categories. The section also carries the utility requirement: the invention must have a specific, substantial and credible use.

The hard part is not in the text. The Supreme Court has long held that laws of nature, natural phenomena and abstract ideas are not patentable, even when they are new. Under Alice and Mayo, a court asks two questions. First, is the claim directed to one of those exceptions? If so, do the remaining elements, alone or in combination, add an inventive concept that amounts to significantly more than the exception itself?

The USPTO applies its own version of that test in MPEP 2106. Step 1 checks the statutory category. Step 2A asks whether the claim recites a judicial exception (prong one) and, if it does, whether the claim integrates it into a practical application (prong two). Only claims that fail prong two go on to Step 2B, which asks whether the additional elements are significantly more than the exception. Software, business methods, diagnostics and claims to natural products draw most of the section 101 rejections.

Annotation by Raj Sutariya, Co-founder, PatentAssist.ai. General information, not legal advice; the statute below governs.

Text of 35 U.S.C. 101

Current text, quoted from the official United States Code.

Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.

Key cases

Diamond v. Chakrabarty, 447 U.S. 303 (1980). A genetically engineered bacterium is a patentable manufacture or composition of matter. The question is whether the subject matter is a product of human ingenuity, not whether it is alive.
Bilski v. Kappos, 561 U.S. 593 (2010). The machine-or-transformation test is a useful clue but not the only test for process claims. The claimed method of hedging risk was an unpatentable abstract idea.
Mayo Collaborative Servs. v. Prometheus Labs., Inc., 566 U.S. 66 (2012). Claims that apply a natural correlation (drug metabolite levels and dosing) using only well-understood, routine and conventional steps are not eligible.
Association for Molecular Pathology v. Myriad Genetics, Inc., 569 U.S. 576 (2013). Isolating a naturally occurring DNA segment does not make it eligible; synthetic complementary DNA (cDNA) that does not occur in nature can be.
Alice Corp. Pty. Ltd. v. CLS Bank Int'l, 573 U.S. 208 (2014). Implementing an abstract idea (intermediated settlement) on a generic computer does not make it eligible. Set out the two-step framework used today.
Enfish, LLC v. Microsoft Corp., 822 F.3d 1327 (Fed. Cir. 2016). Claims directed to a specific improvement in how a computer operates (a self-referential database table) are not directed to an abstract idea at step one.

Practical notes

Write the specification so it can carry a practical-application argument later. Describe the technical problem, the specific technical solution and why it works better, in terms of the machine or process, not the business result. Claims that recite a particular way of achieving the improvement survive more often than claims that recite the result with “a processor configured to” language.

The USPTO's eligibility guidance keeps moving. Its subject matter eligibility page lists an advance notice of MPEP changes in light of Ex parte Desjardins (December 5, 2025) and memoranda on subject matter eligibility declarations (SMEDs), which are 37 CFR 1.132 declarations offering evidence on eligibility, the latest dated September 29, 2026. Check that page before answering a 101 rejection.

Eligibility is decided claim by claim. Dependent claims that add concrete technical detail give you fallback positions in an office action response, and an interview is often the fastest way to learn which limitation the examiner would accept.

Utility rejections are rare outside chemistry and biotechnology. Where they occur, the usual answer is evidence or a clear statement in the specification of a specific and substantial use (MPEP 2107).

Related rules and guidance

37 CFR: § 1.104, § 1.111, § 1.132
MPEP: 2104, 2105, 2106, 2107