What is an abstract idea in patent law?

An abstract idea is one of three judicial exceptions to patent-eligible subject matter under 35 U.S.C. § 101, alongside laws of nature and natural phenomena. The exception exists because abstract ideas represent the basic tools of scientific and technological work, and allowing any single party to monopolize them through a patent would impede rather than promote innovation.

Courts have declined to formally define the term, instead identifying the category through case-by-case analysis organized around enumerated groupings. The USPTO codified that case law into three groupings under its 2019 Revised Patent Subject Matter Eligibility Guidance: mathematical concepts, certain methods of organizing human activity, and mental processes.

The three groupings

Mathematical concepts

Mathematical concepts include mathematical relationships, mathematical formulas or equations, and mathematical calculations. The grouping covers both symbolic and textual forms of mathematical expression: a claim reciting "determining a ratio of A to B" raises the same eligibility question as one written in algebraic notation. What matters is whether the claim amounts to no more than a mathematical operation, not whether it uses mathematical symbols.

Certain methods of organizing human activity

Certain methods of organizing human activity include fundamental economic principles or practices (such as hedging, insurance, and mitigating risk), commercial or legal interactions (such as contracts, agreements, advertising, and marketing), and managing personal behavior or relationships or interactions between people (such as social activities, teaching, and following instructions). The word "certain" is deliberate: not every business practice is per se abstract, only those fitting the enumerated sub-categories as confirmed by case law. A novel industrial process that generates economic output may still be patent-eligible if it produces a defined technical result and is drafted to emphasize that result.

Mental processes

Mental processes are concepts performed in the human mind, including observations, evaluations, judgments, and opinions, as well as methods that can be performed by a human using pen and paper. A method claim whose broadest reasonable interpretation encompasses purely mental execution falls within this grouping. Reciting a computer as the implementing tool does not automatically remove a claim from this category if the computer performs no function beyond what a person could do mentally.

The landmark cases

The abstract idea doctrine developed through a sequence of Supreme Court decisions spanning more than four decades.

Gottschalk v. Benson (1972)

In Gottschalk v. Benson, 409 U.S. 63 (1972), the Supreme Court held that a method for converting binary-coded decimal numerals to pure binary numerals was not patentable because granting the patent would wholly pre-empt use of the underlying mathematical formula. The Court's concern was scope: a patent on the algorithm would effectively monopolize the mathematical concept itself, with no application-specific limit on its reach.

Parker v. Flook (1978)

In Parker v. Flook, 437 U.S. 584 (1978), the Supreme Court held that post-solution activity alone cannot transform an unpatentable mathematical principle into a patentable process, because the mathematical formula was the sole novel feature of the application. The application had surrounded a formula for updating alarm limits in catalytic conversion processes with conventional pre-solution steps (measuring variables) and post-solution steps (adjusting a control setting). Because the formula was the only novel contribution, those surrounding steps did not confer eligibility.

Diamond v. Diehr (1981)

In Diamond v. Diehr, 450 U.S. 175 (1981), the Supreme Court held that incorporating the Arrhenius equation into a process for curing synthetic rubber was patent-eligible subject matter because the claim as a whole performed a physical transformation of raw rubber into cured products. The Court held that a claim drawn to otherwise statutory subject matter does not become ineligible simply because it uses a mathematical formula. Diehr is the clearest expression of what saves an abstract-idea-adjacent claim: the formula operated as one integrated step in a larger physical manufacturing process, so the claim was directed to that process, not to the formula itself.

Bilski v. Kappos (2010)

In Bilski v. Kappos, 561 U.S. 593 (2010), the Supreme Court held that hedging financial risk in energy markets was an abstract idea because it was a fundamental economic practice long prevalent in commerce. Bilski extended the exception beyond mathematical algorithms to cover economic and business concepts, even when no arithmetic formula is explicitly recited.

Alice Corp. v. CLS Bank International (2014)

In Alice Corp. v. CLS Bank International, 573 U.S. 208 (2014), the Supreme Court held that intermediated settlement, implemented on a generic computer, was an abstract idea and therefore ineligible for patent protection. Conventional or generic computer implementation of an abstract idea does not transform the idea into patent-eligible subject matter, because adding routine and conventional activity is insufficient to supply an inventive concept. Alice is the governing precedent for software and business method eligibility: it makes plain that reciting a computer as the implementing tool does not rescue a claim that is otherwise directed to an abstract economic concept.

The Alice/Mayo two-step framework

Because abstract ideas are not categorically excluded from all patent claims (only claims directed to them are ineligible), eligibility turns on how the claim is drafted. The Alice/Mayo two-step framework asks first whether a claim is directed to an abstract idea, and if so, whether the claim's additional elements supply an inventive concept sufficient to transform the nature of the claim into a patent-eligible application.

Step 2A: Is the claim directed to an abstract idea?

Step 2A applies a two-prong approach.

Prong One identifies whether the claim recites a judicial exception. Under Prong One of the USPTO's 2019 Revised Guidance, an examiner determines whether a claim recites a judicial exception by identifying specific claim language that falls within the three enumerated groupings of abstract ideas. A claim that merely involves an abstract idea without explicitly reciting it does not require further eligibility analysis; only claims that recite a judicial exception trigger the full two-step inquiry.

Prong Two asks whether the recited exception is integrated into a practical application. Under Prong Two, a claim is not directed to an abstract idea if additional claim elements integrate the recited exception into a practical application, imposing a meaningful limit on the abstract idea and producing a concrete real-world result. A claim that passes Prong Two is patent-eligible without further analysis.

Step 2B: Does the claim add significantly more?

Step 2B applies only when a claim fails both prongs of Step 2A. It asks whether the claim's additional elements, individually or as an ordered combination, amount to significantly more than the judicial exception itself. Conventional computer components, routine data-gathering steps, and well-understood post-solution activity do not satisfy this threshold.

Landmark outcomes at a glance

Practical notes for practitioners

• Evaluate the claim as an integrated whole. The abstract idea inquiry looks at what the claim as a whole is directed to. A claim is not abstract merely because it uses a mathematical formula or references a business process; the question is whether the overall claim goes beyond the abstract idea and ties it to a specific practical result.
• The mental-steps trap. A method claim that could be performed entirely in a person's head, with no physical constraint, is almost certainly directed to a mental process. The fix is structural: specify the physical implementation, the technical output, or the real-world transformation the method produces. Cognitive steps articulated without any hardware or physical-world constraint will almost always fail Step 2A Prong One.
• Generic computer recitation does not rescue a claim. Reciting a processor or computer alongside abstract method steps adds nothing to the eligibility analysis if the hardware is used in a conventional way. The specification should identify a specific technical improvement, and the claims should reflect that improvement with limiting language tied to the technical context.
• Prong Two is the primary lever. Most § 101 rejections for abstract ideas are better addressed at Step 2A Prong Two (practical application) than at Step 2B (significantly more). A claim integrating an abstract idea into a defined technical context, with specific structural or functional constraints, avoids being directed to the exception in the first place and exits the analysis at eligibility without needing an "inventive concept" argument.
• Maintain diverse claim formats. Method, system, and apparatus claims directed to the same invention may survive different § 101 challenges. A system claim that recites specific structural components may integrate the same abstract idea into a practical application more clearly than a bare method claim reciting only cognitive or computational steps.