American Medical Systems, Inc. v. Biolitec, Inc., No. 2009-1323 (Fed. Cir. Sept. 13, 2010).

The holders of a patent claiming various methods and devices for vaporizing tissue by using laser radiation appealed an order granting summary judgment of noninfringement. The district court based its summary judgment order on its conclusion that the accused device did not perform “photoselective vaporization of tissue,” a term that is contained only in the preambles of the asserted claims.

Finding that the disputed preamble term does not limit the asserted claims, the Federal Circuit reversed. The majority explained that “[w]hile there is no simple test for determining when a preamble limits claim scope, [the Federal Circuit has] set forth some general principles to guide that inquiry.” In general, the preamble does not limit the claims. For example, it is not regarded as limiting when the claim body describes a structurally complete invention such that deletion of the preamble phrase does not affect the structure or steps of the claimed invention or if the preamble is reasonably susceptible to being construed to be merely duplicative of the limitations in the body of the claim (and was not clearly added to overcome a prior art rejection). However, a preamble 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.”

Here, 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. Moreover, the preamble term “photoselective vaporization of tissue” did not provide a necessary antecedent basis for the term “the tissue” in the bodies of each of the independent claims. Most importantly, the descriptor “photoselective” did not embody an essential component of the invention—it was instead simply a descriptive name for the invention that was fully set forth in the bodies of the claims.

Judge Dyk dissented, arguing for a complete overhaul of the principles for determining when a preamble should be limiting. He noted that “[o]ver the years our court has struggled to make sense of when a preamble should be construed as limiting,” and has “not succeeded in articulating a clear and simple rule.” Judge Dyk advocated for a rule “recognizing that all preambles are limiting,” arguing there is “little to be said in favor of allowing an applicant, in the claim drafting process, to include material in the claims that is not binding.” Such a uniform rule “would ensure the patentee has the burden of drafting a patent that avoids confusion as to the scope of the claims.”

A copy of the opinion can be found here.