In American Medical Systems, Inc. v. Biolitec, Inc. (Fed. Cir. 2010) at least one judge in the Federal Circuit agrees that the time has come for the court to address en banc the issue of preambles serving as substantive claim limitations.

This infringement case involves patent No. 6,986,764, (the '764 patent) which relates to a technology for vaporizing tissue using laser radiation. The dispute on appeal turned on whether the preamble constituted a limitation. Claim 31 is representative:

A method for photoselective vaporization of tissue, comprising:

delivering laser radiation to a treatment area on the tissue, the laser radiation having a wavelength and having irradiance in the treatment area sufficient to cause vaporization of a substantially greater volume of tissue than a volume of residual coagulated tissue caused by the laser radiation, wherein the delivered laser radiation has an average irradiance in the treatment area greater than 10 kiloWatts/cm2 in a spot size at least 0.05 mm2.

In general, a preamble limits the invention if it recites essential structure or steps, or if it is necessary to give life, meaning, and vitality to the claim. Conversely, a preamble is not limiting where a patentee defines a structurally complete invention in the claim body and uses the preamble only to state a purpose or intended use for the invention. Catalina Mktg. Int'l, Inc. v., Inc., 289 F.3d 801, 808 (Fed. Cir. 2002) (internal citation and quotations omitted).

During claim construction of the '764 patent, the district court determined that the preamble phrase “photoselective vaporization” was a “fundamental characteristic” of the invention, and construed the term to mean “using a wavelength that is highly absorptive in the tissue, while being absorbed only to a negligible degree by water or other irrigant.” Based on this construction, the court granted summary judgment in favor of the accused infringer.

On appeal, the majority of the Federal Circuit disagreed, concluding that the preamble phrase “photoselective vaporization of tissue” does not limit the claims of the '764 patent. The court explained that if the patent owner wanted to claim the “photoselective vaporization of tissue,” it should have been placed as a limitation in the body of the claim. Judge Dyk dissented, and argued for a blanket rule that the preamble always acts as a claim limitation:

It seems to me that a rule recognizing that all preambles are limiting would make better sense and would better serve the interests of all concerned. There is, after all, 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. If patentees are allowed to include material in the claim definitions that is not binding, patentees can suggest or imply one position before the U.S. Patent & Trademark Office ("PTO") to secure allowance of the patent on the theory that the preamble is limiting and another, inconsistent position in infringe-ment litigation on the theory that it is not limiting. Principles of fairness thus dictate that the patentee should be required to clearly define the claimed invention's scope. By creating a uniform rule that all preambles are limiting, we would ensure the patentee has the burden of drafting a patent that avoids confusion as to the scope of the claims.