How Broadly Can I Claim?

The short version

Broad claims are not forbidden. They are expensive, and they are expensive in two separate currencies. Enablement asks whether the specification lets a skilled person make and use everything claimed. Written description asks whether it shows the inventor actually possessed it. A patent can satisfy one and fail the other.

Amgen and Juno are never published alone, because fixing one problem while believing you have fixed both is the failure mode. The pages below add the same full-scope logic applied to a dosage range, and what the Patent Office tells examiners to look for during examination.

Both decisions concern claims defined by what something does rather than what it is, which is a shape that recurs constantly in software. A claim to any system that achieves a result is functionally the same move as a claim to any antibody that binds a target.

Two requirements, two failure modes. In Amgen, the Supreme Court held that two proposed methods for finding the rest of a claimed class amounted to "little more than two research assignments." That is enablement. In Juno, a specification disclosed two examples of an enormous functional class and a $1.2 billion verdict fell, because two examples did not show possession of the class. That is written description. A specification can teach how to make things and still fail to show the inventor had the category in hand.

The Three Requirements of Section 112(a)

What 35 U.S.C. 112(a) requires of a specification, as the statute states it and as MPEP 2161 separates it into "the three separate and distinct requirements of 35 U.S.C. 112(a)". As of 22 August 2026.
Requirement The statute's words The question it asks The page on this site
Written description"The specification shall contain a written description of the invention"Did the inventor possess what is claimed, at filingShowing possession of what you claim
Enablement"and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art" to make and use itDoes the specification teach a skilled reader to make and use the full claimed scope without undue experimentationThe Wands factors
Best modeThe specification "shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention"Did the inventor disclose the best way they knewThree requirements in one sentence

The manual is explicit that written description "is separate and distinct from the enablement requirement", which is what the two decisions below illustrate from opposite ends: Amgen failed enablement, Juno failed written description, and each specification might have survived the other test. For software, where a competent engineer can often build from a functional description alone, enablement is the easier of the two and written description is where broad claims fail.

The statute never uses the words written description, enablement or definiteness as labels; the doctrines are named after the section, and the names come from elsewhere. And it says nothing about drawings, which live in section 113 and 37 C.F.R. 1.84.

The Decisions

Decision Court Decided In one line
Amgen v. Sanofi Supreme Court 18 May 2023 If you claim a whole category, your patent has to teach how to make the whole category.
Juno v. Kite Federal Circuit 26 August 2021 Describing two members of a huge class is not describing the class, and it cost $1.2 billion.
Wyeth v. AstraZeneca Federal Circuit 9 July 2026 A dosage range the specification cannot support is an enablement problem, not an FDA question.
Amgen v. Sanofi Two methods for finding the rest of a claimed class were "little more than two research assignments." Breadth is allowed; it has to be paid for in disclosure. Read the Case Juno v. Kite Two examples of an enormous functional class did not show the inventor possessed the class. A section 112 case where the number is the consequence, not the subject. Read the Case Wyeth v. AstraZeneca A dosage range the specification cannot support is an enablement problem, not an FDA question. Read the Authority Showing possession Flow charts are not required, says one passage. Function-only description may lack support, says another. They are in the same section for a reason. Read the Page Enablement and Wands The word doing the work is undue. Almost every invention requires some experimentation. Read the Page Three requirements Describing a function is not, by itself, describing an invention. Read the Page

What These Pages Do Not Decide

  • How broad your claims should be. Neither decision says narrow claims are the answer; both say breadth has to be matched by disclosure.
  • Whether your specification enables or supports your claims.
  • What structural characteristics would suffice. Juno was explicit that missing sequences were not the fatal defect, which means the answer is specific to what is claimed.

Educational, not legal advice. Consult a qualified patent attorney about claim scope and the disclosure that has to carry it.

Related

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