Patent claim construction is a fundamental issue in any patent infringement litigation. It is the process by which a court or other tribunal determines the scope and meaning of a patent’s claims.
In most patent infringement litigation cases, the process begins with:
- The Court first construes the patent claims, and
- The Court then evaluates the construed claims against the allegedly infringing device or process.
Claim construction is also important in certain Patent Office proceedings concerning the patentability of a claimed invention, for example, in pre-grant and post-grant filings. Likewise, patent validity determinations are based on the construed patent claims.
Essentially, the concept of claim construction was cemented by US Supreme Court decision in Markman v. Westview Instruments Inc. In this decision, the Court says that claim construction is a question of law reserved for the court and not a question of fact left to the fact finder. Most of the other countries follow a similar approach in patent infringement litigation.
Because proper claim construction begins with an analysis of the intrinsic evidence, claim construction is case-specific. An interpretation of a claim term in one case may be completely different from the interpretation of that same term in another case, especially where the fields of technology are different.
Patent claim terms are generally given their ordinary and customary meaning as understood by a Person of Ordinary Skill in the Art (if possible). The context in which the terms appear in the claim as a whole is an important consideration in claim construction. If the patentee uses different terms to identify similar claim limitations, those terms should have different meanings.
The specification is also highly relevant to the claim construction analysis. For example, the specification may aid in claim construction where it describes the invention’s preferred or sole embodiment or specifically excludes an embodiment from the invention; or distinguishes prior-art or cites particular advantages over the prior-art. That said, it is often subtle to construe the claims in light of the specification and improperly importing a limitation, e.g., a definition of a term, from the specification into the claims.