What is Patent Eligible Subject Matter?

There are different kinds of patent protection under US patent law. Typically, when one thinks about "patentable subject matter", they are thinking about an invention. Patents that cover an invention (e.g., a new device, method, composition of matter, etc.) are utility patents. There are several patentability requirements for utility patents. An invention is evaluated by the US Patent and Trademark Office under the following four statutory categories: patent eligible subject matter (the right kind of thing), novelty (it must not have been done/made before), nonobviousness (minimal changes to existing technology are not enough), and clarity and enablement (the invention must be functional and properly described). The invention must meet each of these requirements to qualify for a patent. This article provides an explanation of what qualifies as patent eligible subject matter - the kind of thing that can be patented.

Patent Eligible Subject Matter under the US Patent Act

Subject matter eligibility under U.S. patent law requires an invention to meet specific criteria set forth in 35 U.S.C. § 101. This statute outlines four categories of patentable subject matter: processes (methods - series of steps or acts), machines, manufactures, compositions of matter, or a new and useful improvement thereof.

New and Useful Process-

An eligible method invention involves a series of steps or actions to achieve a specific result. For example, consider a novel method for manufacturing a semiconductor device. The claimed method might involve a series of steps such as depositing layers of materials, patterning them using photolithography, and etching to create microstructures. This claimed method would fall under the process category and could be eligible for a process patent if it meets other criteria, such as novelty and non-obviousness. Here are some further examples of new and useful process subject matter:

  • Method for purifying water: A series of steps involving filtration, chemical treatment, and UV exposure.
  • Software algorithm for data encryption: A sequence of steps for encrypting and decrypting data using a specific algorithm.
  • Manufacturing process for solar panels: Steps for assembling solar cells, coating them, and integrating them into panels.


Machines are tangible devices or apparatuses designed to perform specific functions. For instance, an innovative robotic arm used in manufacturing that includes new and useful improvements over existing technology can be patented. This robotic arm might integrate advanced sensors, AI algorithms for precision, and energy-efficient motors, making it a valuable invention in the field of automation.

A more familiar example is the computer. Patents on computer hardware innovations, such as faster processors, more efficient cooling systems, or improved data storage solutions, fall under the machine category. These innovations must be concrete and specific, avoiding abstraction to meet the criteria for patent eligibility. Here are some further examples of appropriate subject matter under the machine category:

  • 3D printer: A device that creates three-dimensional objects from digital files by layering materials.
  • Automated packaging machine: A machine that packages products into boxes and seals them.
  • MRI scanner: A medical device that uses magnetic fields and radio waves to create detailed images of the organs and tissues in the body.


The manufacture category includes items that are made or produced, often through industrial processes. For example, a new type of biodegradable plastic, created by synthesizing polymers from renewable resources, could be patented. This new material, which decomposes more quickly than conventional plastics, addresses environmental concerns and represents a significant advancement in materials science. Here are some further examples of appropriate subject matter under the manufacture category:

  • Smartphone case: A protective cover designed and manufactured for smartphones.
  • Plastic water bottle: A bottle made from plastic, designed to hold liquids.
  • LED light bulb: A light-emitting diode bulb manufactured for energy-efficient lighting.

Compositions of Matter

This category includes chemical compositions and compounds. Pharmaceuticals are a prime example. A new drug that effectively treats a disease with fewer side effects represents a patentable composition of matter. The patent application would cover the specific chemical structure of the drug, which is proper subject matter under section 101.

  • Pharmaceutical drug: A new chemical compound developed for treating a specific medical condition.
  • Polymer blend: A specific combination of polymers designed for enhanced durability and flexibility.
  • Genetically modified bacteria: Bacteria engineered to break down environmental pollutants.

Improvements on Statutory Categories

Improvements on existing technologies form a significant category of patentable subject matter, often leading to incremental but valuable advancements in various fields. According to the Patent Act, any new and useful improvement of a process, machine, manufacture, or composition of matter can be patented. The essence of this category lies in enhancing the functionality, efficiency, or utility of existing inventions, making them more effective or adaptable. Here are some examples:

  • Medical Devices:
    • Improving traditional stents used in angioplasty procedures by introducing drug-eluting functionality, which release medication to prevent artery re-blockage. This new and useful improvement enhances patient outcomes by reducing the likelihood of complications.
  • Automotive Technology:
    • Enhancements in internal combustion engines that improve fuel efficiency, such as variable valve timing systems, may represent patentable improvements. These systems optimize the engine's performance and reduce emissions, offering significant benefits over traditional engines.
  • Consumer Electronics:
    • Smartphones: Innovations in smartphone technology, like enhanced battery designs or improved camera systems, are often incremental improvements on existing devices.
  • Renewable Energy:
    • Solar Panels: Improvements in solar panel technology, such as the development of more efficient photovoltaic cells, increase energy conversion rates and reduce costs. These advancements make solar energy more viable and accessible, would reflect a patentable improvement in the field.

Patentable improvements drive technological progress by building on existing inventions. These new and useful enhancements not only offer practical benefits but also qualify for patent protection, encouraging continuous innovation and development across various industries.

Judicial Exceptions and the Alice/Mayo Test

While an invention must fall into a statutory category to be patent eligible, fitting into one of these categories alone does not guarantee patent subject matter eligibility. The Supreme Court has established an exclusionary principle that holds that a claimed invention that is directed to an abstract ideas, laws of nature, or a natural phenomena cannot be patented. These judicial exceptions are based on the concern that granting patents for "basic tools of scientific and technological work" would impede innovation, rather than promote it. Gottschalk v. Benson, 409 U.S. 63 (1972). This principle was reinforced by the Supreme Court in cases such as Alice Corp. v. CLS Bank Int’l and Mayo Collaborative Services v. Prometheus Laboratories, Inc., which established a two-part test for determining patent eligibility.

  1. The first step of the test assesses whether the claimed subject matter is directed to one of the judicial exceptions. If the answer is yes, the second step examines whether the claim elements, individually or as an ordered combination, amount to significantly more than the judicial exception. This means that the claim recites additional elements that transform the abstract idea into a patent eligible application.
  2. The second step involves searching for an inventive concept. An inventive concept must go beyond the unpatentable abstract idea, law of nature, or natural phenomenon itself and must include additional elements that ensure the claim amounts to significantly more than the judicial exception. These elements are evaluated individually and in combination to determine if they contribute an inventive concept that provides something more than an existing technology or existing technological process. The evaluation must consider all elements of the claimed invention and ensure they provide more than well-understood, routine, conventional activities. This inventive concept is distinct from novelty or non-obviousness and must be identified to make a claim patent-eligible under 35 U.S.C. § 101. If there is an inventive step beyond the judicial exception, then the claim may be patent eligible.

If the claim includes a judicial exception, it will likely be rejected by a patent examiner. However, if there is a novel, innovative concept within the claim, the inventive aspect may be sufficient to confer patent eligibility to the patent claim. The following is an example of a claimed invention that includes an natural phenomenon, but also includes an inventive concept that may overcome a judicial exception rejection under the natural phenomenon exclusion.

Alice/Mayo Analysis Example based on Supreme Court Guidance

A claim for a method for diagnosing a disease may include obtaining a blood sample from a subject; determining the presence or absence of a biomarker in the blood sample by using a specific reagent that selectively binds to the biomarker; comparing the level of the biomarker in the blood sample to a predetermined threshold level; diagnosing the subject with the disease if the level of the biomarker is above the predetermined threshold level and the reagent is a novel engineered protein that improves the specificity and sensitivity of the biomarker detection. The claim involves a method of diagnosing a disease, which falls under the category of "laws of nature" or "natural phenomenon." This is because the correlation between the biomarker level and the disease is a natural phenomenon.

Subject Matter Eligibility Analysis

Despite involving a judicial exception, the claim includes a novel engineered protein. The inclusion of a novel engineered protein as a specific reagent that selectively binds to the biomarker is a concrete and inventive step. This protein improves the specificity and sensitivity of the biomarker detection compared to existing methods, thus adding man-made chemical that is significantly more than just the natural correlation. The novel engineered protein provides a technological improvement created by the scientific and technological work of man, which is a significant step beyond the abstract idea or natural law. The method claim satisfies as a whole demonstrates a practical application of the natural correlation in a way that provides improved diagnosis, a tangible and useful result.

USPTO Patent Examination Approach for Analyzing Patentable Subject Matter

The United States Patent and Trademark Office (USPTO) employs a meticulous approach when analyzing patentable subject matter, ensuring that each application meets statutory requirements before granting patent rights. A key aspect of this examination is claim interpretation, specifically under the broadest reasonable interpretation (BRI) standard. This method plays a crucial role in determining whether an invention encompasses subject matter eligible for patent protection.

Claim Interpretation under Broadest Reasonable Interpretation

When evaluating a patent application, the USPTO applies the broadest reasonable interpretation to the claims. This means that the claims are interpreted in their broadest form consistent with the specification as understood by someone skilled in the art. The purpose of this approach is to establish a clear boundary of what the patent covers, thus ensuring that the claims are not interpreted in an unduly broad or vague manner. This claim construction is essential in identifying claims that meet the criteria for patentability.

Evaluating Eligibility Based on Claim Interpretation

The BRI standard affects the evaluation process by ensuring that the claim interpretation affects the breadth and scope of the claimed invention. The examiner determines if the interpreted claim encompasses subject matter that falls into one of the statutory categories. The examiner also assesses whether the claim is directed to a patent ineligible concept such as an abstract idea, law of nature, or natural phenomenon.

Determining Patent Eligibility

To determine patentability, the examiner conducts the following detailed analysis of the claims:

  1. Claim Construction: Using the BRI standard, the examiner constructs the claim to ascertain its broadest reasonable meaning.
  2. Evaluating Eligibility:
    1. The examiner evaluates whether the claimed invention falls into one of the patent eligible categories: compositions of matter, processes, machines, manufactures, or an improvement thereof. If the claims do not fall into a statutory category, they are patent ineligible. If they do fall into a statutory category, the examiner moves to the evaluation of whether the claims cover a judicial exception.
    2. The examiner evaluates the claims to ensure that they do not fall within the judicially recognized exceptions (abstract ideas, laws of nature, or natural phenomena).
    3. If the claim falls within a judicial exception, the examiner then assesses whether additional elements in the claim transform the nature of the claim into a patent-eligible application.

Addressing Patent Ineligibility

When a claim is found to be patent ineligible, the examiner provides a detailed explanation, identifying the specific reasons for ineligibility. This includes discussing how the claim falls within a judicial exception and lacks additional elements that confer patentability. Applicants may then respond by amending claims or providing arguments to demonstrate eligibility. The USPTO’s approach to claim interpretation under the broadest reasonable interpretation standard is a cornerstone in the patent examination process. The goal of the BRI standard is clarity and precision in determining patentability, thereby maintaining a balanced system that fosters innovation while preventing overly broad or ambiguous claims. By carefully evaluating eligibility based on this standard, the USPTO ensures that only inventions meeting stringent criteria are awarded patent protection, thus upholding the integrity of the patent system.

Patent Protection is Available for a Wide Variety of Technologies

The patent law encompasses a wide range of technologies across various statutory categories. Understanding subject matter eligibility is crucial for inventors and practitioners to navigate the complexities of the Patent Act. While judicially recognized exceptions like laws of nature, natural phenomena, and abstract ideas present challenges, the inclusion of inventive concepts and practical applications can transform these exceptions into patentable subject matter. By ensuring that a claim satisfies the criteria for patent eligibility, inventors can secure exclusive rights to their innovations, driving progress and benefiting society at large.

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