Understanding patent claim construction is a challenging, but vital enterprise in any patent suit. Claim construction is the process by which a court interprets the terms found in a patent claim to determine the following: a) their validity; b) whether they read upon a product or device; c) infringement (literal or doctrine of equivalence); d) non-infringement; e) anticipation; or f) obviousness.
However, courts perform the claim construction analysis in the context of the following: a) written description; b) the prosecution history of the patent; and c) extrinsic evidence. In performing this analysis, the court may not read additional limitations into the claims and cannot redefine the terms of the claims. Generally, the court will not interpret all terms within a claim, but only those claim terms identified as material and relevant by the parties.
In performing this analysis, the court must consider a variety of factors and principles, but it need not consider all of them. The following are a list of the factors and principles the Court may consider:
1) the type of claim at issue (Jepson, means plus function, independent v. dependent, etc…);
2) the relevant inquiry must be performed within the context of a person of ordinary skill in the art at the time of invention;
3) generally claims terms are given their customary and ordinary meaning;
4) the terms should be considered in context of other terms within the claim (i.e. rendering other terms superfluous, consistent use throughout, etc..);
5) the terms should be considered in accordance with the principles of claim differentiation–(meaning two claims should not be interpreted to contain exactly the same limitations);
6) the definition provided to the term by a patentee (the patentee may act as his or her own lexicographer);
7) the specification or written description is generally the best indicator of the meaning of a term (reference to preferred embodiment of invention or invention as a whole, structural or functional construction, etc…);
8) the prosecution history (how the patentee or examiner interpreted the terms during the prosecution process, arguments relating to the meaning of the terms in responding to office actions, traversing objections, re-examinations, reissuance or interference proceedings);
9) the industry, trade or dictionary definition of the claim term;
10) dependent claims should be interpreted more narrowly than independent claims;
11) use of different terms in different claims generally means a difference in meaning and scope of claims;
12) extrinsic evidence (testimony offered by an expert, meaning ascribed in other references during the time of invention, etc…).
For an example of how courts perform the patent claim construction analysis see:
American Pile Driving. Courts generally perform the claim construction analysis during Markman hearings. Claim construction is a vital part of any patent dispute.