United States Court of Appeals 

for the Federal Circuit 

__________________________ 

AMERICAN MEDICAL SYSTEMS, INC. 

AND LASERSCOPE, 

Plaintiffs-Appellants, 

v. 

BIOLITEC, INC., 

Defendant-Appellee. 

__________________________ 

2009-1323 

__________________________ 

Appeal from the United States District Court for the 

District of Massachusetts in case no. 07-CV-30109, 

Judge Michael A. Ponsor. 

___________________________ 

Decided: September 13, 2010 

___________________________ 

LELAND G. HANSEN, McAndrews, Held & Malloy, Ltd., 

of Chicago, Illinois, argued for plaintiffs-appellants. With 

him on the brief was SCOTT P. MCBRIDE. 

MARK D. GIARRATANA, McCarter & English, LLP, of 

Hartford, Connecticut, argued for defendant-appellee. 

With him on the brief were ERIC E. GRONDAHL and 

CHARLES D. RAY. 

__________________________ 
AMERICAN MEDICAL v. BIOLITEC 2

Before BRYSON, DYK, and PROST, Circuit Judges. 

Opinion for the court filed by Circuit Judge BRYSON. 

Dissenting opinion filed by Circuit Judge DYK. 

BRYSON, Circuit Judge. 

In this patent infringement action, plaintiffs American Medical Systems, Inc., and Laserscope appeal an 

order granting summary judgment of noninfringement to 

defendant Biolitec, Inc. The patent in suit, Laserscope’s 

U.S. Patent No. 6,986,764 (“the ’764 patent”), is entitled 

“Method and System for Photoselective Vaporization of 

the Prostate, and Other Tissue.” It claims various methods and devices for vaporizing tissue by using laser radiation. The district court based its summary judgment 

order on its conclusion that Biolitec’s accused device does 

not perform “photoselective vaporization of tissue,” a term 

that is contained only in the preambles of the asserted 

claims. Because we conclude that the disputed preamble 

term does not limit the asserted claims, we reverse and 

remand. 

I 

The invention of the ’764 patent can be used to treat 

Benign Prostatic Hyperplasia (“BPH”), a condition in 

which growth of the prostate gland restricts the passage 

of urine out of the bladder and through the urethra. 

Vaporization, or ablation, of some of the prostate tissue 

reduces the size of the prostate and can relieve bladder 

outlet obstructions. As described in the patent, 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-
3 AMERICAN MEDICAL v. BIOLITEC

intensity laser radiation to the target tissue by means of 

an optical fiber. 

According to the specification of the ’764 patent, prior 

art tissue vaporization systems were inefficient when 

used with continuous irrigation, and they frequently 

caused side effects including residual tissue coagulation, 

i.e., the generation of a layer of thermally denatured 

tissue, which led to swelling, transient urinary retention, 

and infection. ’764 patent, col. 2, ll. 33-41. The ineffectiveness of the prior art systems was due in part to their 

use of longer wavelengths of laser radiation, such as 2100 

or 1064 nanometers (“nm”). At 2100 nm, the specification 

explains, laser radiation is “strongly absorbed by water in 

the prostate tissue” and there is “essentially no selective 

absorption by blood.” When combined with the pulse 

energies and pulse durations used in the prior art devices, 

the use of radiation of that wavelength led to violent 

tissue disruption and “poor hemostasis” (stoppage of 

bleeding). Id., col. 2, ll. 17-20, 28-32. At 1064 nm, the 

radiation is hemostatic when used at high power levels, 

but has low absorption in blood and prostate tissue that 

“leads to inefficient ablation and a large residual layer of 

thermally denatured tissue several millimeters thick.” 

Id., col. 2, ll. 36-38. By contrast, the specification explains, laser radiation at a wavelength of 532 nm “is 

selectively absorbed by blood, leading to good hemostasis,” 

and when sufficient power is used at that wavelength, the 

process leaves behind a layer of denatured tissue less 

than 1 millimeter thick, which reduces swelling and 

painful urination. Id., col. 2, ll. 49-56. The specification 

adds, however, that even when using a wavelength of 532 

nm, prior art techniques were inefficient and caused 

significant residual coagulation. Id., col. 2, ll. 59-65. 
AMERICAN MEDICAL v. BIOLITEC 4

The inventors of the ’764 patent determined 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 residual coagulation. The 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. 

Claim 31 is representative of the method claims. It 

recites: 

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. 

The apparatus claims are generally similar, except that 

they also recite a laser and an endoscope having an optical fiber for delivering the laser radiation. 
5 AMERICAN MEDICAL v. BIOLITEC

Most of the independent claims do not specify a 

maximum or minimum wavelength for the laser radiation 

used in the claimed methods or by the claimed apparatus, 

although several of them have dependent claims specifying that “the laser radiation has a wavelength in a range 

from about 650 to about 200 nm.” The other independent 

claims expressly recite “laser radiation having a wavelength in a range of about 200 nm to about 650 nm.” With 

the exception of claims 1 and 16, all of the independent 

claims contain limitations requiring that the laser radiation have a “wavelength and 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.” Claim 1 

requires that the laser radiation be “absorbed substantially completely by the tissue within about 1 mm of the 

surface,” and that it have “average irradiance in the 

treatment area greater than 10 kiloWatts/cm2 in a spot 

size at least about 0.05 mm2.” Claim 16 requires the 

delivery of laser radiation and a flow of transparent liquid 

irrigant, with the laser “causing vaporization of a volume 

of tissue greater than a volume of residual coagulation of 

tissue, and having irradiance in the treatment area 

greater than 10 kiloWatts/cm2 in a spot size at least about 

0.05 mm2.” 

The plaintiffs filed suit against Biolitec in the United 

States District Court for the District of Massachusetts, 

alleging that Biolitec’s EvolveTM laser system and method 

of use infringed a number of the claims of the ’764 patent. 

The accused product is a laser-powered tissue ablation 

system that uses radiation having a wavelength of 980 

nm. It includes an optical fiber probe for administering 

the radiation by direct contact with the target tissue. 
AMERICAN MEDICAL v. BIOLITEC 6

Following a Markman hearing, the district court issued an order construing several key terms in the asserted claims. Am. Med. Sys., Inc. v. Biolitec, Inc., 569 F. 

Supp. 2d 313 (D. Mass. 2008). Most sharply disputed 

were the terms in the preambles of the asserted claims: 

“A method for photoselective vaporization of tissue” and 

“An apparatus for photoselective vaporization of tissue.” 

The plaintiffs argued that the preamble language (particularly the phrase “photoselective vaporization”) simply 

describes the invention as a whole and should not be 

construed as a limitation of any of the asserted claims. 

The district court, however, ruled that the repeated use of 

the phrase “photoselective vaporization” in the specification and claims indicated that “photoselective vaporization” is a “fundamental characteristic” of the invention, 

albeit not its central innovative feature. Id. at 320-22. 

The court found support for that conclusion in the patent’s discussion of the prior art. In particular, the court 

relied on the patent’s criticism of earlier laser systems 

that used longer wavelengths of 2100 nm or 1064 nm. 

Those systems, according to the specification, produced 

“low” or “no” selective absorption of the radiation by blood 

and tissue; by contrast to those systems, the specification 

praised a prior art system that used a shorter wavelength 

of 532 nm that was “selectively absorbed by blood.” Id. at 

321. Accordingly, the court construed the term “photoselective vaporization” 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.” Id. at 

327. 

In light of the district court’s claim construction ruling, Biolitec moved for summary judgment of noninfringement, asserting that its EvolveTM laser system 

operated at a wavelength (980 nm) at which the energy is 

absorbed to more than “a negligible degree by water or 
7 AMERICAN MEDICAL v. BIOLITEC

other irrigant.” The district court granted Biolitec’s 

motion. Am. Med. Sys., Inc. v. Biolitec, Inc., 603 F. Supp. 

2d 251 (D. Mass. 2009). The court began by noting certain undisputed facts concerning the properties of 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). For example, the 

absorption coefficient of 980 nm laser energy in water is 

0.43, whereas the absorption coefficient of 532 nm laser 

energy in water is only 0.00036; and 4.2% of 980 nm laser 

energy is absorbed by water at a distance of 1 mm from 

prostate tissue, whereas only 0.004% of 532 nm laser 

energy is absorbed by water at that distance. Id. at 255-

56. The district court also observed that Biolitec’s accused device operates by placing the device in direct 

contact with the target tissue so as to prevent absorption 

of the energy by the water irrigant. In light of those facts, 

the court concluded that “[w]hen compared to 532 nm 

laser light, 980 nm laser light is more than negligibly 

absorbed by the water irrigant” and thus did not satisfy 

the “photoselective vaporization” limitation of the ’764 

patent, as the district court construed it. Id. at 256. The 

court therefore held that Biolitec’s accused device did not 

literally infringe the ’764 patent. 

The district court also addressed the issue of infringement under the doctrine of equivalents. The court 

concluded that the “function-way-result” test was illsuited to evaluating the patent in suit, but it held that 

under the “all limitations” rule and the corollary “specific 

exclusion” principle developed by this court, Biolitec’s 

device did not infringe the ’764 patent by equivalents. 

Am. Med. Sys., 603 F. Supp. 2d at 257-58. 

On appeal, the plaintiffs contend that (1) the term 

“photoselective vaporization” in the preamble of each of 
AMERICAN MEDICAL v. BIOLITEC 8

the asserted claims should not be construed as a claim 

limitation; (2) if “photoselective vaporization” is a limitation on the claims, the district court erred in construing 

that term to require a wavelength that is “absorbed only 

to a negligible degree by water or other irrigant”; and (3) 

if the district court’s claim construction is correct, the 

district court erred in its infringement analysis in several 

respects. We conclude that the preamble phrase “photoselective vaporization of tissue,” and particularly the descriptor “photoselective,” does not limit the claims of the 

’764 patent. Therefore, we need not address the plaintiffs’ 

remaining arguments. Because the district court’s grant 

of summary judgment was predicated entirely on its 

conclusion that Biolitec’s accused device “does not violate 

the ‘photoselective vaporization’ claim limitation in the 

’764 patent as construed in the Markman Order,” Am. 

Med. Sys., 603 F. Supp. 2d at 256, we reverse and remand 

for further proceedings. 

II 

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.” Storage Tech. Corp. v. Cisco Sys., Inc., 329 F.3d 

823, 831 (Fed. Cir. 2003). While there is no simple test 

for determining when a preamble limits claim scope, we 

have set forth some general principles to guide that 

inquiry. “Generally,” we have said, “the preamble does 

not limit the claims.” Allen Eng’g Corp. v. Bartell Indus., 

Inc., 299 F.3d 1336, 1346 (Fed. Cir. 2002). Nonetheless, 

the 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.” Catalina Mktg. 

Int’l, Inc. v. Coolsavings.com, Inc., 289 F.3d 801, 808 (Fed. 

Cir. 2002), quoting Pitney Bowes, Inc. v. Hewlett-Packard 
9 AMERICAN MEDICAL v. BIOLITEC

Co., 182 F.3d 1298, 1305 (Fed. Cir. 1999). A preamble is 

not regarded as limiting, however, “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.” Catalina, 289 

F.3d at 809. 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), we do not construe it to 

be a separate limitation.” Symantec Corp. v. Computer 

Assocs. Int’l, Inc., 522 F.3d 1279, 1288-89 (Fed. Cir. 2008). 

We have held that the preamble has no separate limiting 

effect if, for example, “the preamble merely gives a descriptive name to the set of limitations in the body of the 

claim that completely set forth the invention.” IMS Tech., 

Inc. v. Haas Automation, Inc., 206 F.3d 1422, 1434-35 

(Fed. Cir. 2000). 

In light of those principles, we conclude that the preamble language in the asserted claims of the ’764 patent 

does not constitute a limitation of the claims. More 

specifically, we reject the district court’s suggestion, 

implicit in its claim construction and infringement analyses, that the preamble descriptor “photoselective” limits 

the claims to a particular (albeit unspecified) range of 

wavelengths at which laser radiation is “absorbed only to 

a negligible degree by water or other irrigant.” 

First, there is no suggestion in the prosecution history 

of the ’764 patent 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. 
AMERICAN MEDICAL v. BIOLITEC 10

Second, contrary to Biolitec’s argument, the preamble 

term “photoselective vaporization of tissue” does not 

provide a necessary antecedent basis for the term “the 

tissue” in the bodies of each of the independent claims. 

The preamble’s reference to “vaporization of tissue” does 

not specify a particular type or location of tissue being 

treated. Nor does the generic term “tissue” in the preamble provide any “context essential to understand[ing]” the 

meaning of “the tissue” in the body of each claim. 

Seachange Int’l, Inc. v. C-COR, Inc., 413 F.3d 1361, 1376 

(Fed. Cir. 2005). Thus, the claim drafters did not rely on 

the preamble language to define or refine the scope of the 

asserted claims. See Catalina, 289 F.3d at 808 

(“[D]ependence on a particular disputed preamble phrase 

for antecedent basis may limit claim scope because it 

indicates a reliance on both the preamble and claim body 

to define the claimed invention.”). 

Third, and most importantly, the descriptor “photoselective” does not embody an essential component of the 

invention. Instead, the term “photoselective vaporization” 

is simply a descriptive name for the invention that is fully 

set forth in the bodies of the claims. See Storage Tech., 

329 F.3d at 831 (preamble term “policy caching method” 

did not limit claims because it served only as a “convenient label for the invention as a whole”). The bodies of the 

asserted apparatus claims (claims 63-64) describe a 

structurally complete device, including a laser adapted to 

deliver “radiation at a wavelength and irradiance . . . 

sufficient to cause [tissue] vaporization[.]” The bodies of 

those claims identify the covered wavelengths by function 

(“sufficient to cause vaporization”), and nothing in the 

claim language suggests that the term “photoselective” 

further limits those wavelengths. The inference that the 

asserted apparatus claims do not require the use of energy of a particular wavelength is considerably strength-
11 AMERICAN MEDICAL v. BIOLITEC

ened by the fact that a number of other apparatus claims 

(claims 59-62 and 67-74), which contain the same disputed preamble language, limit the wavelength of the 

radiation to the range from “about 200 nm to about 650 

nm.” If the term “photoselective” were deemed independently limiting, it would either be redundant or in conflict 

with the specific wavelength range set forth in the body of 

those claims. 

The apparatus claims make clear that one can practice the invention without using wavelengths in the 200 to 

650 nm range described by the ’764 specification as having “strong oxyhemoglobin absorption” and “relatively 

weak water absorption,” as long as the energy applied is 

sufficient to “cause vaporization of a substantially greater 

volume of tissue than a volume of residual coagulated 

tissue.” That point is underscored by the fact that the 

apparatus claims reciting the 200 to 650 nm range also 

require a lower minimum irradiance, which indicates that 

the purpose of the claims is to maximize volumetric power 

density through different combinations of variables; the 

’764 patent thus contemplates that with an increase in 

the laser’s wavelength, more power will be necessary to 

vaporize the tissue and minimize coagulation. 

Likewise, the bodies of the asserted method claims 

contain all the steps necessary to practice the invention. 

Independent claims 16, 31, 36, 40, and 42 require the 

delivery of radiation “causing” or “sufficient to cause” 

vaporization “of a substantially greater volume of tissue 

than a volume of residual coagulated tissue.” Independent claim 1 does not explicitly require vaporization, but it 

requires that the laser radiation be “absorbed substantially completely by the tissue within 1 mm of the surface.” Thus, in each of the asserted method claims, as in 

the apparatus claims, the invention is recited in func-
AMERICAN MEDICAL v. BIOLITEC 12

tional terms; as long as the stated objective is achieved, 

through the 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.” While, as a practical matter, use of a wavelength of laser radiation that is selectively absorbed by 

tissue to at least some degree will likely be necessary to 

satisfy the functional requirements, the claim language 

does not require any particular wavelength range (or 

upper limit). 

As in the case of the apparatus claims, other claims 

among the method claims provide strong support for the 

plaintiffs’ argument that the asserted method claims are 

not limited to wavelengths having a prescribed degree of 

differential absorption in tissue and water. Method 

claims 1, 16, and 31 each have dependent claims that 

recite the use of wavelengths “from about 200 nm to about 

650 nm.” Under the doctrine of claim differentiation, 

those dependent claims give rise to a presumption that 

the broader independent claims are not confined to that 

range. Phillips v. AWH Corp., 415 F.3d 1303, 1315 (Fed. 

Cir. 2005) (en banc). Thus, in every asserted claim of the 

’764 patent, the language in the body of the claims recites 

a complete invention for achieving the stated purpose of 

applying laser radiation in a high volumetric power 

density. Removal of the duplicative preamble language 

would neither alter the scope of the claims nor introduce 

ambiguity as to their coverage. 

The specification of the ’764 patent further confirms 

that “photoselective vaporization” is a label for the overall 

invention and not a limitation on the claims. Although 

the phrase “photoselective vaporization” appears in the 
13 AMERICAN MEDICAL v. BIOLITEC

title, in the abstract, and six times in the rest of the 

written description, it is consistently used in reference to 

the entire invention’s emphasis on improved vaporization 

efficiency through high power densities. The broad recitation in the “Field of Invention,” which states that “[t]he 

present invention relates generally to laser treatment of 

soft tissue, and more particularly to photoselective vaporization of the prostate PVP, and to photoselective 

vaporization of other tissue,” supports the plaintiffs’ 

position that the phrase is meant to serve as a label for 

the invention as a whole. The other references to the 

term, including those in the abstract and in a key passage 

cited by the district court, also indicate that the phrase 

“photoselective vaporization” describes the overall invention. 

The district court based its claim construction largely 

on the following sentence in the specification (’764 patent, 

col. 3, line 66, through col. 4, line 6): 

Photoselective vaporization of tissue, such as the 

prostate for treatment of BPH, is based upon applying a high intensity radiation to prostate tissue 

using a radiation that is highly absorptive in the 

tissue, while being absorbed only to a negligible 

degree by water or other irrigant during the operation, at power densities such that the majority 

of the energy is converted to vaporization of the 

tissue without significant residual coagulation of 

adjacent tissue. 

As the court acknowledged, 569 F. Supp. 2d at 322, the 

use of the words “based upon,” rather than “means” or 

“is,” undermines the suggestion that the term “photoselective vaporization” is used as a definition or limitation of 
AMERICAN MEDICAL v. BIOLITEC 14

the claim terms. In any event, however, to the extent 

that the sentence describes “photoselective vaporization,” 

it is not limited to describing radiation with wavelengths 

that are absorbed to a substantially greater degree by 

tissue than by water, but also describes other key aspects 

of the overall invention. Those include the use of high 

irradiance levels to achieve high “power densities” and 

efficient vaporization of tissue, which the district court 

deemed the “central innovative feature” of the invention 

as a whole. Moreover, the sentence’s reference to absorption “during the operation” alludes to the principle, expressed elsewhere in the patent, that in practice the 

irradiance delivered to a treatment area can be increased 

and the absorption of the laser energy in the irrigant 

correspondingly decreased not only by selecting an appropriate wavelength for the laser output, but also by reducing the distance between the optical fiber and the tissue, 

thereby minimizing the amount of liquid through which 

the laser energy must pass. See ’764 patent, col. 5, ll. 52-

59. Thus, we conclude that the quoted sentence, read in 

context, does not use the term “photoselective vaporization” to confine the invention to the use of particular 

wavelengths but is better understood as a description of 

the overall process described and claimed in the ’764 

patent. 

In support of its argument that the term “photoselective” is a limitation on the claims, Biolitec also points to a 

portion of the “Detailed Description” section of the specification, which states, “The 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. . . . The wavelength 

also must be minimally absorbed by the irrigant . . . used 

during the procedure, typically water.” ’764 patent, col. 

12, ll. 16-21. That language indicates that using radiation 
15 AMERICAN MEDICAL v. BIOLITEC

of certain wavelengths may increase the effectiveness of 

the invention, but it does not suggest that the invention is 

limited to particular wavelengths regardless of the values 

of the other variables in a particular device. Although the 

quoted passage expresses a preference for using wavelengths of 200 to 650 nm, other portions of the ’764 specification discuss embodiments using radiation with 

wavelengths up to 1000 nm. ’764 patent, col. 4, ll. 28-29. 

Moreover, as noted, the presence of claims reciting wavelengths of 200 to 650 nm gives rise to the inference that 

the remaining claims, which do not contain that express 

wavelength limitation, read on processes and devices 

using wavelengths outside that range. In addition, the 

specification refers to wavelengths in the 200 to 1000 nm 

range (a range that includes Biolitec’s device, which uses 

radiation of 980 nm wavelength) as the “preferabl[e]” 

wavelengths for use in practicing the invention. ’764 

patent, col. 4, ll. 28-29. 

The dissent argues that, while 200 to 1000 nm wavelengths are described as preferred “for some embodiments,” the “photoselective vaporization embodiment” is a 

“separate embodiment” that “is consistently described as 

having a wavelength in the 200-650 range.” However, the 

’764 specification does not support that interpretation. In 

the sole instance in which an “embodiment” is specifically 

described as involving “photoselective vaporization,” the 

subsequent description expresses no preferred wavelength range. Instead, it provides the following general 

explanation: “According to this embodiment, the method 

includes delivering laser radiation to the treatment 

area . . . wherein the laser radiation has a wavelength 

and irradiance in the treatment area on the surface of the 

tissue sufficient [to cause] vaporization of a substantially 

greater volume of tissue than a volume of residual coagulated tissue caused by the laser radiation.” ’764 patent, 
AMERICAN MEDICAL v. BIOLITEC 16

col. 5, ll. 22-29. Here, as in the patent’s claims employing 

nearly identical language, “photoselective vaporization” 

(the descriptor for the invention as a whole) is expressed 

in functional terms; i.e., as long as the selected wavelength and irradiance together result in “vaporization of a 

substantially greater volume of tissue than a volume of 

residual coagulated tissue,” no particular wavelength 

range is required. The specification does not delineate a 

particular wavelength range until later, when it addresses a more specific embodiment: “In other embodiments, the delivered laser radiation has a wavelength in a 

range of about 200 nm to about 650 nm.” Id., col. 5, ll. 41-

42. The passages cited by the dissent, most of which refer 

to the invention as a whole, do not support the existence 

of a separate “photoselective vaporization embodiment”; 

they 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.1 

Accordingly, the specification as a whole indicates that 

while wavelength is one of the variables employed in the 

invention, the claims (other than those specifically limited 

to 200 to 650 nm) are not limited to particular wave-

 1

 The dissent asserts that the language discussing 

use of wavelengths greater than 650 nm is a remnant of 

an earlier parent patent and was retained in order to 

support additional claims (claims 77-80), which did not 

recite “photoselective vaporization” and were abandoned 

after being rejected as anticipated by prior art. The 

references to longer wavelengths all appeared in the 

initial application for the ’764 patent, however, while 

claims 77-80 were not added until a later amendment. 

That sequence of events suggests that the longerwavelength references were included because the original 

“photoselective vaporization” claims were intended to 

encompass longer wavelengths. 
17 AMERICAN MEDICAL v. BIOLITEC

lengths exhibiting particular levels of differential absorption in tissue and water. 

To be sure, the specification points out the drawbacks 

of prior art lasers that use longer-wavelength radiation to 

perform tissue ablation, noting that 2100 nm radiation 

results in “essentially no selective absorption by blood” 

and that 1064 nm radiation has “low absorption in blood 

and prostate tissue,” leading to inefficient ablation. See

’764 patent, col. 2, ll. 15-41. However, both of those 

examples lie above the 200 to 1000 nm range that the ’764 

specification refers to as “preferabl[e].” The discussion of 

the prior art therefore falls far short of “mak[ing] clear 

that the invention does not include a particular feature,” 

SciMed Life Sys., Inc. v. Advanced Cardiovascular Sys., 

Inc., 242 F.3d 1337, 1341 (Fed. Cir. 2001), and does not 

rise to the level of a disclaimer of wavelengths between 

650 and 1000 nm. 

Read as a whole, the ’764 patent discloses methods 

and devices for increasing power density in the application of laser energy, which may be achieved in ways that 

do not require a specific wavelength range. Other variables (including, e.g., irradiance, spot size, distance 

between optical fiber and tissue, irrigant type, and output 

power) are incorporated in various combinations in the 

independent and dependent claims, which suggests that 

while selection of an appropriate wavelength is one means 

by which the objectives set forth in the asserted claims 

can be achieved, no particular wavelength range is required by the claims. 

III 

For the foregoing reasons, we conclude that the district court erred when it construed the phrase “photose-
AMERICAN MEDICAL v. BIOLITEC 18

lective vaporization” as a claim limitation, rather than 

merely a label for the invention as a whole. We therefore 

reverse the summary judgment of noninfringement and 

remand for further proceedings addressing whether 

Biolitec’s accused device meets the remaining claim 

limitations of the ’764 patent. 

REVERSED AND REMANDED
United States Court of Appeals 

for the Federal Circuit 

__________________________ 

AMERICAN MEDICAL SYSTEMS, INC. 

AND LASERSCOPE, 

Plaintiffs-Appellants, 

v. 

BIOLITEC, INC., 

Defendant-Appellee. 

__________________________ 

2009-1323 

__________________________ 

Appeal from the United States District Court for the 

District of Massachusetts in case no. 07-CV-30109, Judge 

Michael A. Ponsor. 

__________________________ 

DYK, Circuit Judge, dissenting. 

I respectfully dissent from the majority’s decision that 

the preamble is not a claim limitation. 

I 

Under our precedent, a preamble is construed as limiting “if it recites essential structure or steps, or if it is 

‘necessary to give life, meaning, and vitality’ to the claim,” 

but not if “the claim body describes a structurally com-
AMERICAN MEDICAL v. BIOLITEC 2

plete invention.”1 Over the years our court has struggled 

to make sense of when a preamble should be construed as 

limiting. See Bell Commc’ns Research, Inc. v. Vitalink 

Commc’ns Corp., 55 F.3d 615, 620 (Fed. Cir. 1995) (“Much 

ink has, of course, been consumed in debates regarding 

when and to what extent claim preambles limit the scope 

of the claims in which they appear.”). 

As the majority itself appears to recognize, we have 

not succeeded in articulating a clear and simple rule. 

Majority Op. at 8; see also Patrick J. Flinn, Claim Construction Trends in the Federal Circuit, 572 PLI/PAT 317, 

335-36 (1999) (characterizing the preamble limitations 

test as “opaque” and without a set framework). As a 

result of the lack of clarity as to whether a preamble 

should be construed as limiting, our case law has become 

rife with inconsistency, both in result and in the articulation of the test.2 As the leading treatise on patent law 

 1

 Catalina Mktg. Int’l, Inc. v. Coolsavings.com, Inc., 

289 F.3d 801, 808, 808-09 (Fed. Cir. 2002) (quoting Pitney 

Bowes, Inc. v. Hewlett-Packard Co., 182 F.3d 1298, 1305 

(Fed. Cir. 1999)). 2

 See Bicon, Inc. v. Straumann Co., 441 F.3d 945, 

952 (Fed. Cir. 2006) (“While it is true that preamble 

language is often treated as nonlimiting in nature, it is 

not unusual for this court to treat preamble language as 

limiting, as it is in this case.”); Storage Tech. Corp. v. 

Cisco Sys., Inc., 329 F.3d 823, 831 (Fed. Cir. 2003) 

(“Whether to treat a preamble 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.”); 

Catalina Mktg., 289 F.3d at 808 (Fed. Cir. 2002) (“No 

litmus test defines when a preamble limits claim scope.”). 

Compare DeGeorge v. Bernier, 768 F.2d 1318, 1322 n.3 

(Fed. Cir. 1985) (stating that “[g]enerally, and in this 

case, the preamble does not limit the claims”), with Bell 

Commc’ns, 55 F.3d at 621 (noting that the observation in 

DeGeorge that the preamble does not generally limit the 

claims “can only have been de scriptive, rather than pre
3 AMERICAN MEDICAL v. BIOLITEC

observes, “the decisions are difficult to reconcile.” 3 

Donald S. Chisum, Chisum on Patents § 8.06[1][d] (2010). 

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 infringement litigation on the theory that it is not limiting.3 

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. As the Supreme Court concluded in 

Merrill v. Yeomans, 94 U.S. 568, 573-74 (1876), “nothing 

can be more just and fair, both to the patentee and to the 

public, than that the former should understand, and 

 

scriptive. . . . [O]ne cannot determine a preamble’s effect 

except by reference to the specific claim of which it is a 

component”). 

3

 Of course, if the patentee makes his or her positions explicit, the patentee could be barred by the doctrine 

of prosecution history estoppel from taking such inconsistent positions. But, in many cases, it is not readily apparent whether the patentee has taken inconsistent 

positions. 
AMERICAN MEDICAL v. BIOLITEC 4

correctly describe, just what he has invented, and for 

what he claims a patent.” 

Neither the Supreme Court nor our court sitting en 

banc has ever addressed the preamble limitation issue. I 

think the time may have come for us to eliminate this 

vague and confusing rule. 

II 

Even under our existing precedent, which is binding 

on the panel, I believe that the preamble term “photoselective vaporization” should have been construed as a 

claim limitation. The determination of whether a preamble serves as a claim limitation is “resolved only on review 

of the entire[ ] . . . patent to gain an understanding of 

what the inventors actually invented and intended to 

encompass by the claim.” Corning Glass Works v. Sumitomo Elec. U.S.A., Inc., 868 F.2d 1251, 1257 (Fed.Cir. 

1989); see also Applied Materials, Inc. v. Advanced Semiconductor Materials Am., Inc., 98 F.3d 1563, 1572-73 

(Fed. Cir. 1996) (“Whether a preamble stating the purpose 

and context of the invention constitutes a limitation of the 

claimed process is determined on the facts of each case in 

light of the overall form of the claim, and the invention as 

described in the specification and illuminated in the 

prosecution history.”). A preamble generally limits an 

invention if it recites essential structure or steps or if it is 

“necessary to give life, meaning, and vitality” to a claim. 

Catalina Mktg., 289 F.3d at 808 (quoting Pitney Bowes, 

182 F.3d at 1305). 

In my view, the photoselective vaporization language 

must be treated as a claim limitation. U.S. Patent No. 

6,986,764 (“the ’764 patent”) was a continuation-in-part of 

U.S. Patent No. 6,554,824 (“the ’824 patent”). Neither the 

’824 application nor the issued ’824 patent used the term 

“photoselective vaporization” in the claims or in the 
5 AMERICAN MEDICAL v. BIOLITEC

specification. The addition of the term “photoselective 

vaporization” in the preamble of the claims of the ’764 

patent was significant. The applicant took considerable 

care to add new matter to the specification describing and 

defining photoselective vaporization. The term appears in 

the title of the patent (once), the abstract (once), the Field 

of the Invention section (twice), the Summary of the 

Invention section (twice), and the Detailed Description 

section (once). For example, the Field of the Invention 

section states: “The present invention relates generally to 

laser treatment of soft tissue, and more particularly to 

photoselective vaporization of the prostate PVP, and to 

photoselective vaporization of other tissue.” ’764 Patent, 

col.1 ll.33-36 (emphases added). 

The Summary of the Invention section of the specification defines “photoselective vaporization” as follows:

Photoselective vaporization of tissue, such as the 

prostate for treatment of BPH, is based upon applying a high intensity radiation to prostate tissue 

using a radiation that is highly absorptive in the 

tissue, while being absorbed only to a negligible 

degree by water or other irrigant during the operation, at power densities such that the majority 

of the energy is converted to vaporization of the 

tissue without significant residual coagulation of 

adjacent tissue. 

Id. col.3 l.66-col.4 l.6. In light of this passage, the District 

Court properly construed “[a] method for photoselective 

vaporization of tissue”/“[a]n apparatus for photoselective 

vaporization of tissue” 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.” 

Am. Med. Sys., Inc. v. Biolitec, Inc., No. 07-30109-MAP, 
AMERICAN MEDICAL v. BIOLITEC 6

slip op. at 38 (D. Mass. July 31, 2008). Photoselective 

vaporization is a product of shortening the wavelengths of 

the emitted signal. 

The majority appears to conclude that reading photoselective vaporization as a clear limitation would be 

inconsistent with the specification, which contemplates 

wavelengths up to 1000 nm. In my view, the majority 

misconstrues the specification and prosecution history. 

As the majority points out, the original ’824 patent 

was concerned, among other things, with reducing the 

wavelength of the laser light over the prior art. As the 

majority recognizes, the specification repeatedly criticizes 

the prior art use of “earlier laser systems that used longer 

wavelengths of 2100 nm or 1064 nm.” Majority Op. at 6. 

The ’824 patent reduced the claimed wavelengths to the 

200 to 1000 nm range, and the specification stated that 

the “wavelength of the laser light is preferably between 

200 and 1000 nm.” ’764 Patent col.4 ll.28-29; see ’824 

Patent col.3 ll.44-45. 

The continuation-in-part application that became the 

’764 patent further reduced the claimed ranges. The 

claims of the ’824 patent were amended to eliminate 

wavelengths in the 650-1000 range and to substitute 

references to wavelengths in the 200-650 range for the 

original wavelength range of 200-1000 nm in the claims 

where a specific range is included. See J.A. 893-903. 

While the specification continued to mention wavelengths 

in the 200-1000 range as “preferred” for some embodiments, the specification makes clear that the photoselective vaporization embodiment is a separate embodiment, 

stating that “one embodiment of the invention provides a 

method for photoselective vaporization of prostate tissue.” 

’764 patent col.5 ll.21-22. The specification states that for 

that invention “it is desirable to provide a wavelength 
7 AMERICAN MEDICAL v. BIOLITEC

between 650 and 200 nm.” Id. col.16 ll.32-33. The photoselective vaporization embodiment is never described as 

having a wavelength in the 200-1000 range. Rather, it is 

consistently described as having wavelengths in the 200-

650 range.4 The specification repeatedly touts the advantages of photoselective vaporization, that is, the “532 nm 

light from these lasers is selectively absorbed by blood 

leading to good hemostasis” and more efficient tissue 

ablation. ’764 Patent col.2 ll.49-59. 

If there were any doubt that photoselective vaporization is a claim limitation, it is resolved by the specification’s statement that “[t]he wavelength used according to 

the present invention for BPH treatment should be 

 4

 See, e.g., ’764 patent col.12 ll.16-34 (“The 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 

without creating deep tissue heating. The wavelength 

also must be minimally absorbed by the irrigant it used 

during the procedure, typically water. The 532 nm light 

produced by the system of FIG.5, is both strongly absorbed in oxyhemoglobin and weakly absorbed in water. . . . In yet other embodiments, wavelengths in the 

range from 200 nm-500 nm are used, which have strong 

oxyhemoglobin absorption and relatively weak water 

absorption . . . .”); id. col.14 ll.57-59 (“KTP laser energy 

will be generated by a high power 532 nm laser capable of 

delivering 80W of KTP laser power to tissue.”); id. col.15 

ll.25-55 (comparing the 1064 nm wavelength used in the 

prior art to the 532 nm wavelength and concluding that 

the 532 laser beam is preferable because it is “substantially completely absorbed within less than about 1 mm of 

the surface of prostatic tissue. . . . The coagulation zone is 

very thin because of the small optical penetration depth of 

the 532 wavelength. . . . Other wavelengths which are 

substantially completely absorbed within less than about 

1 mm of the surface of the prostatic tissue include wavelengths less than about 650 nm, for example between 

about 200 nm and 650 nm.”). 
AMERICAN MEDICAL v. BIOLITEC 8

strongly absorbed in the prostate tissue to help initiate 

and maintain tissue vaporization. . . . The wavelength 

also must be minimally absorbed by the irrigant . . . used 

during the procedure, typically water.” ’764 Patent col.12 

ll.16-21 (emphases added). While this sentence appears 

in the Detailed Description section of the specification, we 

have repeatedly held that “the use of the words ‘the 

present invention’ can be read to limit the invention to 

what is described as such.” Martek Biosciences Corp. v. 

Nutrinova, Inc., 579 F.3d 1363, 1383 (Fed. Cir. 2009) 

(citing Honeywell Int'l, Inc. v. ITT Indus., Inc., 452 F.3d 

1312, 1318 (Fed. Cir. 2006)); see Trading Techs. Int’l, Inc. 

v. eSpeed, Inc., 595 F.3d 1340 (Fed. Cir. 2010) (holding 

that the reference to the system of the present invention 

strongly suggests that the claimed re-centering command 

requires a manual input); Chimie v. PPG Indus., Inc., 402 

F.3d 1371, 1379 (Fed. Cir. 2005) (noting that “when the 

preferred embodiment is described in the specification as 

the invention itself, the claims are not necessarily entitled 

to a scope broader than that embodiment”); Honeywell, 

452 F.3d at 1318 (construing claim term to include fuel 

filter because “[o]n at least four occasions, the written 

description refers to the fuel filter as ‘this invention’ or 

‘the present invention’”). Minimal absorption by the 

irrigant and strong absorption by tissue, or photoselective 

vaporization, are thus mandatory aspects of this particular invention. 

I recognize, as the majority points out, that the specification for the ’764 patent includes references to wavelengths that are not photoselective because they are not 

“minimally absorbed.” ’764 Patent col.8 ll.7-12 (“Other 

laser systems may be used . . . which are adapted to 

provide the output power and wavelengths described 

herein, including wavelengths in the ranges from 200 nm 

to 1000 nm and from 1100 nm to 1800 nm, for example.”). 
9 AMERICAN MEDICAL v. BIOLITEC

But as I have noted this language in the specification does 

not relate to the photoselective vaporization embodiment 

and is explained by the fact that the ’824 patent specification included claims that were directed to longer wavelengths. The fact that such language was retained by the 

’764 patent specification is explained by a desire to include additional claims in the ’764 patent not directed to 

the “photoselective vaporization” embodiment. Indeed, a 

preliminary amendment to the ’764 application recited 

seven additional claims (claims 77-80) that did not include the term “photoselective vaporization.” Claim 77 

explicitly described using lasers with a wavelength in the 

200 nm to 1000 nm range. These claims were subsequently abandoned during prosecution after being rejected as anticipated by U.S. Patent Nos. 5,776,175 and 

5,776,127. J.A. 369. 

Under the circumstances, it seems clear to me that 

“photoselective vaporization” should be construed as a 

claim limitation; by adding this terminology during 

prosecution of the ’764 patent, the patentee conceded that 

the term gave life, meaning, and vitality to the claims.5 

Therefore, contrary to the majority, I would hold that 

photoselective vaporization is a claim limitation. 

 5

 As the majority points out, the reference to the 

200 to 650 nm range in the dependent claims (claims 4-6, 

19-21, 32-34, 37, 59-62 and 67-74) suggests that the 

independent claims are broader. See Majority Op. at 11. 

But this merely suggests that the photoselective vaporization limitation applies to somewhat longer wavelengths 

than 200 to 650 nm.