Patents

Brenner v. Manson: Why a Patent Is Not a Hunting License

The Supreme Court held that a novel process for making a chemical with no known use fails the utility requirement, planting the doctrinal seed of 'substantial' utility that still governs the chemical and biotech arts.

February 10, 2025
Glassware and reagents on a chemistry laboratory bench
Manson's process reliably produced a steroid, but the steroid itself had no disclosed practical use. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

Brenner v. Manson, No. 58, was decided by the Supreme Court of the United States on March 21, 1966, after argument on November 17, 1965. Writing for the Court, Justice Abe Fortas delivered the now-canonical formulation that a patent “is not a hunting license” — a single sentence that reoriented the utility requirement of 35 U.S.C. § 101 for the chemical arts and, decades later, for the genomics and biologics bars. The opinion is the headwater of the modern “specific and substantial utility” standard, and it remains the first authority any practitioner reaches for when an applicant claims a compound or process whose practical benefit lies somewhere over the horizon of further research.

At a glance

  • Case: Brenner, Commissioner of Patents v. Manson, No. 58 (U.S.)
  • Decided: March 21, 1966; opinion by Justice Fortas; 7-2 on the utility holding (Harlan, J., joined by Douglas, J., dissenting in relevant part)
  • Posture: Certiorari to the Court of Customs and Patent Appeals, which had reversed the Patent Office Board of Appeals; Supreme Court reversed the CCPA and reinstated the rejection
  • Holding: A novel process for producing a known chemical compound does not satisfy § 101 utility unless the applicant shows a specific, presently available practical use for the product; membership in a class of compounds undergoing screening, and the fact that the process works, are not enough
  • Status: Controlling Supreme Court precedent

The claim and the contested benefit

Andrew Manson sought a patent on a process for making a particular steroid — a homologue of compounds in the broader class of dihydrotestosterone derivatives. The process itself was conceded to be operable: it reliably produced the intended steroid. The difficulty lay one step beyond the reaction vessel. Manson did not disclose a known, practical use for the steroid his process yielded.

He offered two substitutes for such a use. First, he pointed to a published article reporting that a structurally adjacent homologue had shown tumor-inhibiting effects in mice, and argued that chemists would expect his closely related steroid to behave similarly. Second, he urged that his steroid belonged to a class of compounds then being actively screened for biological activity, so that the product had value as an object of scientific investigation. The Patent Office found neither theory sufficient; the CCPA disagreed and ordered the patent to issue. The Commissioner took the case up.

The holding: utility means a benefit in currently available form

The Court reversed. Its reasoning proceeds in two moves that have structured utility doctrine ever since.

The first move rejects the “adjacent homologue” argument as a matter of evidentiary insufficiency married to legal principle. Even granting that chemists might predict activity by analogy, the Court refused to treat a prediction about a neighboring molecule as proof of utility for the claimed one. Manson himself had not shown that his steroid did anything. The Court was unwilling to let structural proximity substitute for a demonstrated benefit, particularly in a field where small structural changes routinely produce large and unpredictable differences in biological effect.

The second move is the one that endures. Manson’s class-screening theory — that the compound was useful because scientists were investigating its family for possible activity — drew the Court’s sharpest response. A compound that is merely the subject of research, the Court held, has not yet achieved utility in the patent sense. “A patent is not a hunting license,” Justice Fortas wrote. “It is not a reward for the search, but compensation for its successful conclusion.” Until a chemical process has been carried “to the point of producing a product shown to be useful, the metes and bounds of that monopoly are not capable of precise delineation.” A patent on such a process, the Court warned, would “engross a vast, unknown, and perhaps unknowable area” and confer “a monopoly of knowledge” that the statute does not authorize absent a showing that “a specific benefit exists in currently available form.”

Why the chemical context mattered

The opinion is sometimes read as a general statement about utility, but its force comes from the peculiar economics of chemical and pharmaceutical research. The Court was acutely aware that a process patent on a compound of unknown use would let the patentee fence off an entire research frontier — every downstream use later discovered by others would fall within a monopoly granted before anyone knew what the compound was good for. That is the precise inversion of the patent bargain: the public would pay the monopoly price before receiving the disclosure of any benefit.

The dissent, by Justice Harlan joined by Justice Douglas, accepted the jurisdictional holding but resisted the utility ruling. Harlan worried that a demanding utility threshold would discourage disclosure of intermediate chemical advances and would withhold patent protection precisely where research investment is most speculative and most needed. The disagreement between the majority and the dissent — protect the public from premature monopolies versus reward early-stage chemical innovation — is the same tension that animates utility disputes in genomics today.

Open questions

Brenner announced a standard more easily stated than applied. How “specific” must a disclosed use be, and how much experimental support must accompany it? The Court did not say. It also left open how its reasoning interacts with the separate enablement and written-description requirements, which can independently police claims to compounds of uncertain function. And because the case concerned a process claim tied to a useless product, courts have since had to work out how its logic maps onto claims to compositions of matter, research tools, and biological sequences — work that culminated, a generation later, in the Federal Circuit’s EST jurisprudence.

Implications

  • Disclose a real use, in present tense. A specification must identify a specific practical benefit available now, not a benefit that further research might reveal.
  • Structural analogy is not utility. Predicted activity based on a related compound will rarely carry the day without data on the claimed subject matter itself.
  • “Being screened” is not a use. Membership in a class of compounds under investigation describes a research program, not a patentable utility.
  • The bargain runs one way. Courts will resist monopolies that precede, rather than follow, the discovery of a benefit — the durable theme that links Brenner to modern § 101 disputes.
  • Process claims inherit the product’s defect. A perfectly operable process can fail § 101 if the thing it makes has no disclosed use.

Frequently asked questions

Did the Court doubt that Manson’s process actually worked? No. Operability was not the issue. The process reliably produced the intended steroid. The defect was that the steroid had no disclosed practical use, and a working process for making a useless product does not satisfy § 101.

Is Brenner v. Manson still good law after later utility cases? Yes. It remains binding Supreme Court precedent and is the foundation on which the Federal Circuit and the Patent Office built the modern “specific, substantial, and credible” utility framework, including the 2001 Utility Examination Guidelines and In re Fisher.

What did “a patent is not a hunting license” come to mean? It became shorthand for the principle that a patent rewards a completed, useful invention — not the mere pursuit of one. An applicant cannot claim a head start on a research field before identifying a concrete benefit the public can use.

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