Free Tool · Claim Linter
Catch claim defects before the examiner does.
Paste a patent claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → and this flags the §112 drafting issues examiners reject on — missing antecedent basis, indefinite terms like 'substantially', means-plus-function language, and the single-sentence rule.
What it checks
Five things examiners reject on
Single-sentence rule
A claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → must be exactly one sentence. Internal periods are a formal defect.
Antecedent basis (§112)
Every "the X" needs an earlier "a X" / "an X" that introduced it — otherwise the claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → is indefinite.
Indefinite terms (§112(b))
Relative words like "substantially", "about", or "high" have no fixed boundary and draw rejections.
Means-plus-function (§112(f))
"Means for …" narrows the claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → to the structure disclosed in your spec — often unintentionally.
Transitional phrase
"Comprising" (open) vs "consisting of" (closed) sets how broadly the claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → reads. Missing one is a red flag.
Heuristic checks for education, not a legal opinion. A registered patent attorney should review any claim before filing. PatentBrief is not a law firm.
FAQ
Frequently asked questions
What is antecedent basis in a patent claim?
Antecedent basis means a term is introduced with 'a' or 'an' the first time it appears, then referred to as 'the' or 'said' afterward. A 'the' with no earlier introduction is an antecedent-basis error examiners reject under §112.
What makes a patent claim indefinite?
A claimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → is indefinite under §112(b) if a skilled reader can't tell what it covers. Vague terms of degree, missing antecedent basis, and inconsistent terminology are the usual culprits — all things a claim checker flags.
Where this fits · The patent process
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