The § 101 categories and judicial exceptions
35 U.S.C. § 101 provides that '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.' This broad statutory language was intended to cover 'anything under the sun that is made by man' (Diamond v. Chakrabarty, S.Ct. 1980). However, courts have carved out three judicial exceptions to § 101 eligibility: laws of nature (mathematical formulas, physical principles, natural relationships), natural phenomena (products of nature, naturally occurring substances), and abstract ideas (mental processes, fundamental economic practices, mathematical concepts). The rationale: these building blocks of science and human thought should be freely available for all to use. The challenge is that nearly every invention involves some element of a natural law or abstract idea — the question is whether the claim is merely directed to the exception itself or to a specific application of it.
Alice Corp. v. CLS Bank (2014) — software patents
Alice Corp. Pty. Ltd. v. CLS Bank International (S.Ct. 2014) applied the Mayo two-step framework to software patents. The claims were directed to a computerized scheme for mitigating settlement risk using an intermediary — a form of intermediate settlement. The Court unanimously held the claims invalid under § 101: Step 1, the claims were directed to an abstract idea (the concept of intermediated settlement); Step 2, using a generic computer to implement the abstract idea did not add an inventive concept. Alice significantly narrowed software patent eligibility. Post-Alice, claims directed to business methods implemented on generic computers, data analysis, or organizing information fail § 101 routinely. The USPTO has issued guidance attempting to systematize the analysis, but the Federal Circuit remains the primary interpreter. Alice has generated thousands of district court decisions and is one of the most invoked patent precedents since it was decided.
Mayo Collaborative Services v. Prometheus (2012) — natural laws
Mayo Collaborative Services v. Prometheus Laboratories, Inc. (S.Ct. 2012) addressed the patentability of diagnostic medical methods. The Prometheus patents claimed a method of adjusting thiopurine drug doses based on metabolite levels: if metabolite levels were too high, reduce dose; if too low, increase dose. The natural relationship between metabolite levels and drug efficacy was a natural law. The Court held: Step 1, the claims were directed to a natural law; Step 2, the additional steps (administering the drug, determining metabolite levels, considering adjustment) were routine and conventional — already done before the patent — and did not add an inventive concept. Mayo has significantly impacted diagnostic, pharmaceutical, and personalized medicine patents. Claims must do more than 'apply it' (the natural law) — they must involve a non-routine, unconventional application of the natural relationship.
What passes § 101 — eligibility factors
Post-Alice/Mayo, patent-eligible claims typically share one or more of: (1) a specific technological improvement in how a computer operates — the Federal Circuit found computer memory management claims eligible in Enfish (2016) because the claims improved computer functionality in a specific way; (2) a new and specific laboratory technique that does not merely observe a natural phenomenon — new primers, specific PCR methods, engineered bacteria (as in Chakrabarty); (3) non-conventional combinations of steps that produce a practical application beyond the natural law or abstract idea; (4) claims directed to a specific physical machine, manufacture, or composition that is not naturally occurring. The USPTO's 2019 Revised Guidance directs examiners to find claims abstract only when they fall into specific groupings: mathematical concepts, certain methods of organizing human activity, and mental processes. This guidance is binding on examiners but not courts.
§ 101 in prosecution and litigation
In USPTO prosecution, § 101 rejections are issued under the Alice/Mayo framework. Applicants respond by: arguing the claim is not directed to an abstract idea or natural law (Step 1 rebuttal); arguing that even if it is, the additional elements provide an inventive concept (Step 2 rebuttal); and/or amending claims to emphasize the specific technical improvement. Claim drafting to survive § 101 involves: including specific technical implementation details rather than functional results; tying claims to specific hardware configurations; emphasizing the technical problem being solved; and demonstrating improvements to computer functionality, not just using a computer to perform a method. In litigation, § 101 challenges are filed early (Rule 12 motions) because they can resolve the case cheaply before discovery. Courts assess eligibility based on the claim language and the patent's specification — a specification that acknowledges the claimed concept is an abstract idea or natural law can undermine eligibility arguments.
Natural products and § 101
Association for Molecular Pathology v. Myriad Genetics (S.Ct. 2013) addressed whether isolated DNA sequences are patent-eligible. The Court held: naturally occurring DNA sequences (including cDNA only to the extent they mirror the natural sequence) are products of nature and ineligible; however, cDNA — which is synthetically created and has a sequence not found in nature — is patent-eligible. Myriad clarified the boundary for biotechnology patents: a naturally occurring product of nature cannot be patented, but a modified or engineered biological product that differs meaningfully from its natural counterpart can be. Diamond v. Chakrabarty (S.Ct. 1980) remains the landmark holding that a bacterium modified to break down crude oil (not naturally occurring in that form) was patent-eligible — 'anything under the sun made by man.' The line between natural products and engineered products often turns on whether the claimed product has markedly different characteristics from its natural counterpart.
Frequently Asked Questions
What is patent subject matter eligibility under § 101?
35 U.S.C. § 101 defines the categories of inventions eligible for patent protection: 'any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof.' However, the Supreme Court has identified three judicial exceptions to § 101 eligibility: laws of nature, natural phenomena, and abstract ideas. These exceptions reflect the principle that basic building blocks of science and thought — mathematical relationships, fundamental natural processes, pure mental operations — should remain in the public domain. § 101 eligibility is separate from novelty (§ 102), nonobviousness (§ 103), and written description/enablement (§ 112). A claim can be novel, nonobvious, and well-described but still fail § 101 if it covers an abstract idea or natural law without more.
What is the Alice/Mayo two-step test for subject matter eligibility?
The Alice/Mayo two-step framework (from Mayo Collaborative Services v. Prometheus Laboratories, S.Ct. 2012, and Alice Corp. v. CLS Bank International, S.Ct. 2014) is used to evaluate whether a claim falls within a judicial exception to § 101. Step 1: Determine whether the claim is directed to a patent-ineligible concept — a law of nature, natural phenomenon, or abstract idea. If no, the claim is eligible. If yes, proceed to Step 2. Step 2 (inventive concept): Determine whether the claim contains an 'inventive concept' sufficient to transform the nature of the claim into a patent-eligible application. The additional elements must be more than well-understood, routine, conventional activity already engaged in by those in the field. Looking at the elements individually and as an ordered combination, ask whether they add 'significantly more' than the ineligible concept itself.
What makes a software patent eligible under § 101?
Software patent claims survive § 101 analysis when they: (1) are directed to a specific improvement in computer functionality (not just performing a conventional computer process more efficiently); (2) use computer technology in a non-generic, non-conventional way to solve a specific technical problem; (3) have claims that, when read as a whole, reflect something other than applying an abstract idea on a generic computer. The Federal Circuit has found software eligible when: the claims improve a specific technical problem in computer networks (Enfish); the claims improve the functioning of a display interface in a specific technical way (Core Wireless); the claims improve speech recognition accuracy through a specific technical means (McRO). Claims that are NOT eligible: mental processes performed on a generic computer; organizing, comparing, or filtering data without a concrete technical improvement; hedging financial risk using routine computer steps; longstanding business practices implemented on generic hardware.
What happened to diagnostic method patents after Mayo?
Mayo Collaborative Services v. Prometheus Laboratories (S.Ct. 2012) struck down a diagnostic patent claiming a method of optimizing drug dosage by measuring metabolite levels in a patient's blood. The Court held the claims were directed to a natural relationship between blood metabolite levels and drug efficacy — a natural law — and that the additional steps (administering the drug, determining levels, considering the need to adjust) were routine, conventional steps that did not add an inventive concept. After Mayo, diagnostic claims that merely detect a natural biomarker and instruct a physician to consider the result face serious § 101 problems. To survive, diagnostic claims generally need: non-conventional measurement techniques; specific treatment steps beyond 'administering' and 'considering'; claims to novel laboratory methods that improve measurement; or claims that are directed to a specific, concrete biological technique rather than the natural relationship between a biomarker and a condition. Vanda Pharmaceuticals v. West-Ward (Fed. Cir. 2018) found a treatment method eligible where it specified a specific dosing regimen, not just an instruction to consider.
Can § 101 rejections be raised at any point in litigation?
Yes. § 101 eligibility is a threshold legal question that can be raised at any stage of patent litigation, including: on a motion to dismiss under Rule 12(b)(6) before any discovery; on a motion for judgment on the pleadings under Rule 12(c); on a motion for summary judgment; at trial; and on appeal. The Supreme Court in Alice Corp. v. CLS Bank noted that the § 101 inquiry does not require claim construction in all cases — courts can often determine eligibility from the claim language and the patent specification. This has made § 101 challenges particularly powerful: defendants can file early, cheap § 101 motions to dismiss without expensive discovery. Post-grant review (PGR) at the PTAB also allows § 101 challenges within 9 months of patent grant. IPR does not cover § 101; it is limited to §§ 102/103.