§112 · Disclosure
Teach the invention, or lose the claim.
A patent is a bargain: a temporary monopoly in exchange for telling the public how the invention works. Section 112 is where you hold up your end — and where thin applications fall apart. These are the disclosure requirements your specification and claims must satisfy.
The requirements
What §112 demands
Each is a separate way an otherwise-novel, non-obvious invention can still be rejected — or invalidated years later.
Written description
§112(a)The specification must describe the invention in enough detail to show that you actually possessed the full invention as of your filing date — not merely that it would be desirable.
Watch · Claiming broadly (e.g. a whole genus) while the spec only describes a few examples. The claim outruns what you disclosed.
Enablement
§112(a)The specification must teach a person of ordinary skill how to make and use the full scope of the claimed invention without 'undue experimentation.' Courts weigh this with the Wands factors.
Watch · A broad claim the disclosure can't actually support across its whole range, so a skilled person would have to invent to fill the gaps.
Definiteness
§112(b)The claims must inform a skilled reader, with reasonable certainty, of the boundaries of the invention. The Supreme Court set this standard in Nautilus v. Biosig Instruments (2014).
Watch · Vague terms of degree ('about,' 'substantially'), inconsistent terminology, or a claim term with no clear meaning in the art.
Best mode
§112(a)At the time of filing, you must disclose the best way you actually knew to carry out the invention — you can't keep the optimal version secret while patenting a worse one.
Watch · Still required, but after the AIA a failure to disclose the best mode can no longer be used to invalidate or render unenforceable an issued claim.
Means-plus-function
§112(f)A claim element written purely as a function ('means for fastening…') is construed to cover only the specific structure disclosed in the specification, plus its equivalents.
Watch · Using functional language without disclosing corresponding structure — which can narrow the claim drastically or render it indefinite.
Check your draft
§112 is the fourth gate.
An invention must also be eligible (§101), novel (§102), and non-obvious (§103). For §112 itself, the claim tools catch the most common problems before an examiner does.
Plain-English education, not legal advice. Written-description and enablement disputes are among the most technical in patent law — for claims that matter, have a registered patent attorney draft and review the specification. PatentBrief is not a law firm.
The four requirements