Claim Drafting and Interpretation
Claim Drafting and Interpretation tests whether claims are clear, supported, and enforceable. The exam favors claim format, transitional phrases, functional language, antecedent basis, and the intrinsic-evidence hierarchy.
Format and transition
A claim has a preamble, a transitional phrase, and a body. "Comprising" is open and permits additional elements; "consisting of" is closed; "consisting essentially of" is semi-closed and allows unrecited materials that do not materially affect the basic characteristics. 37 CFR 1.75 governs form; 35 U.S.C. § 112(b) requires particular and distinct claiming. Dependent claims incorporate the parent by reference.
Definiteness and functional language
Under Nautilus, a claim is indefinite if it fails to inform a skilled artisan with reasonable certainty. "Means for" plus a function triggers § 112(f): the claim covers the structure disclosed in the specification and equivalents. Williamson requires that structure be disclosed; if the specification recites only a function, the claim may be indefinite. Functional language outside § 112(f) must still be supported and definite.
Interpretation
Phillips makes intrinsic evidence-claim language, specification, and prosecution history-the primary source; extrinsic evidence is secondary. Claim differentiation creates a presumption that dependent claims differ in scope. "A" or "an" means one or more unless the specification requires otherwise; "plurality" means at least two.
Worked example
Claim: "A bracket comprising: a base; a plurality of arms extending from the base; and means for locking the base to a rail." "Comprising" allows extra components; "plurality" requires at least two arms. "Means for locking" triggers § 112(f), so the scope is the structures disclosed for locking-say, a clamp and a bolt-plus equivalents. A later recitation of "the arm" lacks antecedent basis because no singular "arm" was introduced.
Traps
Do not use "consisting of" unless you intend a closed claim. Avoid "about" and "substantially" without a discernible boundary. Do not import specification limitations into the claim unless the inventor clearly intended them. Check every "the" and "said" for antecedent basis, and check method-step order.