The “preamble,” or introductory, part of a patent claim is the portion of the claim preceding the “transition” words “comprising” or “consisting of.” Do the terms of the preamble constitute limitations of the claim? Like so much of the law, "it depends." (American Medical Systems, Inc. and Laserscope v. Biolitec, Inc.)
American Medical and Laserscope sued Biolitec, alleging infringement of a patent directed to a tissue vaporization system used in the treatment of enlarged prostate glands. Biolitec moved for a summary judgment of noninfringement, arguing that a term, “photoselective vaporization,” which appeared in the preambles of the asserted claims, was a claim limitation and that it was not found in the accused products. The plaintiffs argued that the term “simply describes the invention as a whole and should not be construed as a limitation.” The trial judge agreed with Biolitec, ruling that the repeated use of the term in the patent specification and claims indicated that it described a “fundamental characteristic” of the invention. He granted the motion and the plaintiffs appealed.
The appellate court began its analysis by stating the applicable legal principles. Whether to treat a preamble term as a claim limitation is “determined on the facts of each case in light of the claim as a whole and the invention described in the patent. Generally, the preamble does not limit the claims.” However, it may be construed as limiting “if it recites essential structure or steps, or if it is necessary to give life, meaning, and vitality to the claim.” If the body of the claim describes a structurally complete invention or is merely duplicative of the limitations in the claim body – and was not added to overcome a prior art rejection – the preamble is not regarded as limiting. A preamble which merely gives a descriptive name to the claimed invention is also not limiting.
Applying these principles, the court concluded that the preamble term “photoselective vaporization” was NOT a limitation. First, there was no suggestion in the prosecution history that the inventors added the phrase “photoselective vaporization” in order to distinguish their invention from the prior art. Second, the preamble term did not provide a necessary antecedent basis for any term in the body of any of the independent claims. Third, and most importantly, the term did not embody an essential component of the invention. Three strikes and the defendant’s argument was out. “Photoselective vaporization” is “merely a label for the invention as a whole.” The summary judgment was reversed and the case remanded.
THE LESSON TO BE LEARNED: Generally, but not always, a preamble term is NOT a limitation.