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Preamble Term That Is Not an Essential Component of the the Invention Should Not Be Construed as a Claim Limitation

09-1323
September 13, 2010

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Last Month at the Federal Circuit - October 2010

Judges: Bryson (author), Dyk (dissenting), Prost

[Appealed from: D. Mass., Judge Ponsor]

In American Medical Systems, Inc. v. Biolitec, Inc., No. 09-1323 (Fed. Cir. Sept. 13, 2010), the Federal Circuit reversed the district court’s grant of SJ of noninfringement, holding that the district court erred when it construed the preamble phrase “photoselective vaporization” as a claim limitation rather than merely a label for the invention as a whole.

American Medical Systems, Inc. and Laserscope brought suit against Biolitec, Inc. (“Biolitec”) for infringement of U.S. Patent No. 6,986,764 (“the ’764 patent”).  The ’764 patent relates to treatments for Benign Prostatic Hyperplasia (“BPH”), a condition in which growth of the prostate gland restricts the passage of urine through the urethra and out of the bladder.  As described in the ’764 patent, vaporization of some of the prostate tissue reduces the size of the prostate and can relieve bladder outlet obstructions.  This type of BPH treatment generally involves the insertion of a cytoscope into the urethra, the provision of an irrigant such as sterile water, and the application of high-intensity laser radiation to the target tissue by means of an optical fiber. 

The ’764 patent discloses that the use of high “volumetric power density,” i.e., a high amount of energy delivered to a given volume of tissue, would result in increased vaporization efficiency while minimizing the side effect of “residual tissue coagulation.”  Accordingly, the ’764 patent is directed to various methods and devices for achieving high volumetric power density for tissue vaporization by manipulating variables such as wavelength, output power, beam quality, irrigant composition, and distance between the optical fiber and the tissue.  Those variables in turn affect the resulting irradiance level, spot size, and absorption depth.

Biolitec’s EvolveTM laser system is a laser-powered tissue ablation system that uses radiation having a wavelength of 980 nm.  It includes an optical fiber for administering the radiation by direct contact with the target tissue.

Before the district court, the parties disputed the proper construction of the preamble term “photoselective vaporization.”  Finding that the specification and claims indicated that “photoselective vaporization” is a “fundamental characteristic” of the invention, the district court 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.”  In light of this claim construction, the district court found that 980 nm laser light (as in the accused product), as compared with 532 nm laser light (the wavelength of the ’764 patent’s preferred and commercial embodiment), is more than negligibly absorbed by the water irrigant, and thus did not satisfy the “photoselective vaporization” limitation.

On appeal, the Federal Circuit determined that the preamble phrase “photoselective vaporization of tissue,” and particularly the descriptor “photoselective,” does not limit the claims of the ’764 patent.  The Court reasoned that the prosecution history of the ’764 patent does not suggest that the inventors added the phrase “photoselective vaporization” in order to distinguish their invention from the prior art.  Rather, the examiner’s primary reason for approval was the claims’ use of high-power densities to vaporize tissue without causing significant residual tissue damage.

In addition, the Court rejected Biolitec’s argument that the preamble term “photoselective vaporization of tissue” provides a necessary antecedent basis for the term “the tissue” in the bodies of each of the independent claims.  The Court found that the preamble’s reference to “vaporization of tissue” does not specify a particular type or location of tissue and does not provide any “context essential to understand[ing]” the meaning of “the tissue” in the body of each claim.  That is, the claim drafters did not rely on the preamble language to define or refine the scope of the asserted claims.

Furthermore, the Court concluded that, “most importantly,” the phrase “photoselective” does not embody an essential component of the invention and is simply a descriptive name for the invention that is fully set forth in the body of the claims.  The Court observed that the bodies of the asserted apparatus claims describe a structurally complete device and that those claims identify the covered wavelengths by function (“sufficient to cause vaporization”), without suggesting that the term “photoselective” further limits those wavelengths.  Additionally, the Court noted that each of the asserted method claims also recites the invention in functional terms.  Thus, as long as the stated objective is achieved through various recited combinations of wavelength, irradiance, output power, spot size, irrigant type, and distance between the optical fiber and the tissue, it is irrelevant whether a particular wavelength is used that would satisfy an independent requirement of being “photoselective.”

The Court further found that the specification of the ’764 patent confirms that “photoselective vaporization” is not a limitation on the claims because the phrase is consistently used in reference to the entire invention’s emphasis on improved vaporization efficiency through high-power densities, and is not limited to describing radiation with wavelengths that are absorbed to a substantially greater degree by tissue than by water.  The Court explained that specification passages delineating particular wavelength ranges merely suggest but do not require the use of certain wavelengths as a means of increasing the invention’s overall effectiveness in conjunction with other variables.  Thus, the Court concluded that while the specification as a whole indicates that wavelength is one of the variables employed in the invention, the claims are not limited to particular wavelengths exhibiting particular levels of differential absorption in tissue and water.  Accordingly, the Court reversed the judgment of the district court.

Judge Dyk dissented from the majority opinion, finding that the preamble term “photoselective vaporization” should have been construed as a claim limitation.  Judge Dyk observed that the parent of the ’764 patent never used the term “photoselective vaporization” in its claims or in its specification, and found that the addition of the term in the preamble of the claims of the ’764 patent was significant.  In particular, Judge Dyk noted that the ’764 patent applicant took considerable care to add new matter to the specification describing and defining photoselective vaporization and to reduce the claimed wavelength ranges.  Furthermore, Judge Dyk found that minimal absorption by the irrigant and strong absorption by the tissue are mandatory aspects of the invention because the specification stated that “[t]he wavelength used according to the present invention for BPH treatment should be strongly absorbed in the prostate tissue to help initiate and maintain tissue vaporization . . . [and] . . . [t]he wavelength also must be minimally absorbed by the irrigant.”  Dyk Dissent at 7-8.  As a result, Judge Dyk concluded that, by adding the term “photoselective vaporization” during prosecution, the patentee conceded that the term gave life, meaning, and vitality to the claims.

Judge Dyk further proposed that the Federal Circuit adopt a uniform rule that all preambles are limiting, and suggested that the Court should sit en banc to “eliminate this vague and confusing rule” as to when a preamble should be construed as limiting.  Id. at 4.

 

Summary authored by Eric K. Chiu, M.D., Esq.