When Construing Claim Scope, Each Word Matters

Posted by Brandon Blackwell on May 9, 2016

In Akzo Nobel Coatings, Inc. v. Dow Chemical Company, the Federal Circuit held that the use of the word “collection” in the phrase “pressurized collection vessel” required that at least some material accumulate within the vessel before infringement occurs. 

What This Means to You

  • When drafting or amending claims, be sure to remove unnecessary words or phrases.

Case Background

Akzo Nobel sued Dow, alleging infringement of U.S. Patent 6,767,956, in which a process for producing a polymer dispersion is claimed.  The claimed process requires that the polymer dispersion enter an outlet and a “pressurized collection vessel.”

The district court construed Akzo Nobel’s claim to require at least some accumulation in the pressurized collection vessel.  The district court held that Dow’s process—in which the polymer dispersion is ejected through heat exchanger piping and subsequently into the ambient atmosphere—did not infringe Akzo Nobel’s claim because Akzo did not produce any evidence that there was any accumulation of the polymer dispersion within Dow’s heat exchanger piping.   The Federal Circuit affirmed.

Decision Analysis

The Federal Circuit held that the phrase “pressurized collection vessel” must be construed to require accumulation because to construe the phrase otherwise would render the term “collection” superfluous.  Citing Merck v. Teva and Power Mosfet v. Siemens, the court noted that a claim construction that gives meaning to all the terms of the claim is preferred over one that does not do so. 

In many circumstances, there may be a desire to add words or phrases to a claim.  For example, words are often added to make claimed phrases more structural to avoid means-plus-function analysis, which generally limits the scope of the claim to the specific structural embodiments described in the specification.  Words might also be added to avoid indefiniteness rejections.  Adding these words, however, will generally lead to a more narrow interpretation of the claim scope.


For patent applicants or patent holders, it is advisable to review the claims at each stage in prosecution to determine whether any terms may be too limiting.  For those accused of infringement, each word of the claim provides an opportunity to argue that the scope should be sufficiently narrow that the allegedly infringing product or process is not infringing. Therefore, each word in a claim should be carefully considered before filing and during prosecution.

Wolf Greenfield's CAFC Blog

Here, Wolf Greenfield attorneys summarize and identify key takeaways from recent patent law cases decided by the U.S. Court of Appeals for the Federal Circuit. View past case summaries here.

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This blog is intended to promote thought and debate on developing areas of the law. The opinions, commentary and characterizations of cases provided on this blog are not legal advice and do not represent the opinions of Wolf Greenfield or its clients.