United States Court of Appeals for the Federal Circuit 

03-1269, -1286 

EDWARD H. PHILLIPS, 

Plaintiff-Appellant, 

v. 

AWH CORPORATION, 

HOPEMAN BROTHERS, INC., and LOFTON CORPORATION, 

Defendants-Cross Appellants. 

Carl F. Manthei, Attorney at Law, of Boulder, Colorado, argued for plaintiff-appellant. 

Mark W. Fischer, Faegre & Benson LLP, of Boulder, Colorado, argued for defendantscross appellants. With him on the brief were Neal S. Cohen and Peter J. Kinsella. Of 

counsel on the brief were Maurice M. Klee, Law Office of Maurice M. Klee, Ph.D., Fairfield, 

Connecticut, and Kenneth C. Bass, III, Sterne, Kessler, Goldstein & Fox, of Washington, 

DC. Of counsel was Scott E. Holwick, Faegre & Benson LLP. 

 

John M. Whealan, Solicitor, United States Patent and Trademark Office, of Alexandria, 

Virginia, argued for amicus curiae United States. With him on the brief were James A. 

Toupin, General Counsel; Cynthia C. Lynch; Linda Moncys Isacson; and Thomas W. 

Krause, Associate Solicitors. Of counsel on the brief were Peter D. Keisler, Assistant 

Attorney General; John J. Fargo, Director, Commercial Litigation Branch, and Anthony J. 

Steinmeyer, Attorney, Appellate Staff, Civil Division, United States Department of Justice, of 

Washington, DC; and William E. Kovacic, General Counsel, and Suzanne T. Michel, Chief 

Counsel for Intellectual Property, Federal Trade Commission, of Washington, DC. 

Robert L. Baechtold, Fitzpatrick, Cella, Harper & Scinto, of New York, New York, for 

amici curiae Novartis Pharmaceuticals Corporation, et al. With him on the brief were 

Nicholas N. Kallas, Stevan J. Bosses, and Brian V. Slater. 

Paul H. Berghoff, McDonnell Boehnen Hulbert & Berghoff LLP, of Chicago, Illinois, for 

amicus curiae Intellectual Property Owners Association. With him on the brief was Joshua 

R. Rich. Of counsel on the brief was J. Jeffery Hawley, President, Intellectual Property 

Owners Association, of Washington, DC. Of counsel was Herbert C. Wamsley, Intellectual 

Property Owners Association. 
Charles W. Bradley, Rader, Fishman & Grauer, PLLC, of Bloomfield Hills, Michigan,

for amicus curiae Charles W. Bradley. 

Henry C. Bunsow, Howrey Simon Arnold & White, LLP, of San Francisco, California,

for amicus curiae AD HOC Committee of Patent Owners in the Wireless Industry. With him

on the brief were Robert C. Laurenson and David W. Long. Of counsel on the brief were 

Robert D. Yeager, Thomas J. Edgington, and Mark G. Knedeisen, Kirkpatrick & Lockhart 

LLP, of Pittsburgh, Pennsylvania.

Alexander C. Johnson, Jr., Marger, Johnson & McCollom, P.C., of Portland, Oregon, 

for amicus curiae Oregon Patent Law Association. 

Alice A. Kipel, Steptoe & Johnson, LLP, of Washington, DC, for amicus curiae

International Trade Commission Trial Lawyers Association. 

Stephen P. McNamara, St. Onge Steward Johnston & Reens LLC, of Stamford,

Connecticut, for amicus curiae Connecticut Intellectual Property Law Association. With him 

on the brief was Richard J. Basile. Of counsel on the brief were William J. Sapone, 

Coleman Sudol Sapone, P.C., of Bridgeport, Connecticut, Michael J. Rye, Cantor Colburn

LLP, of Bloomfield, Connecticut. 

Douglas E. Olson, Paul, Hastings, Janofsky & Walker, LLP, of San Diego, California, 

for amicus curiae San Diego Intellectual Property Law Association. With him on the brief 

were Kurt M. Kjelland, John E. Peterson, and April M. Alex. Of counsel on the brief were

Ned A. Israelsen, Knobbe Martens Olson & Bear, LLP, of San Diego, California, and William 

L. Respess, Nanogen, Inc., of San Diego, California. 

John Will Ongman, Barnes & Thornburg LLP, of Washington, DC, for amicus curiae 

Biotechnology Industry Organization. With him on the brief was Alice O. Martin, of Chicago, 

Illinois. Of counsel on the brief was Stephan E. Lawton, Vice President and General 

Counsel, Biotechnology Industry Organization, of Washington, DC. 

Steve Z. Szczepanski, Kelley Drye & Warren LLP, of Chicago, Illinois, for amicus

curiae Parus Holdings, Inc. With him on the brief was Mary Jo Boldingh. 

Frederick A. Tecce, McShea Tecce, P.C., of Philadelphia, Pennsylvania, for amici 

curiae McShea Tecce, P.C., et al. 

Michael P. Dougherty, Morgan & Finnegan, L.L.P., of New York, New York, for amicus 

curiae Federal Circuit Bar Association. Of counsel on the brief was Charles F. Schill, 

President, Federal Circuit Bar Association, of Washington, DC. 

Edward D. Manzo, Cook, Alex, McFarron, Manzo, Cummings & Mehler, Ltd., of 

Chicago, Illinois, for amicus curiae The Intellectual Property Law Association of Chicago. Of 

counsel with him on the brief were Patrick G. Burns, Greer, Burns & Crain, Ltd., of Chicago,

Illinois, Dean A. Monco, Wood, Phillips, Katz, Clark & Mortimer, of Chicago, Illinois, Bradford 

2
P. Lyerla, Marshall, Gerstein & Borun, of Chicago, Illinois, and Timothy J. Vezeau, Katten 

Muchin Zavis Rosenman, of Chicago, Illinois. 

Maxim H. Waldbaum, Schiff Hardin LLP, of New York, New York, for amicus curiae

Federation Internationale Des Conseils En Propriete Industrielle. Of counsel on the brief

was John P. Sutton, of San Francisco, California. 

Michael R. Dzwonczyk, Sughrue Mion, PLLC, of Washington, DC, for amicus curiae

Sughrue Mion, PLLC. With him on the brief were Frank L. Bernstein of Mountain View, 

California, and Brandon M. White of Washington, DC. 

Sharon A. Israel, Jenkens & Gilchrist, P.C., of Houston, Texas, for amicus curiae

Houston Intellectual Property Law Association. Of counsel on the brief were Jeremy P. 

Welch, Jonathan M. Pierce, and Jeffrey L. Johnson, Conley Rose, P.C., of Houston, Texas. 

George C. Summerfield, Jr., Stadheim & Grear, of Chicago, Illinois, for amici curiae

The Wisconsin Alumni Research Foundation, et al. With him on the brief were Joseph A. 

Grear and Keith A. Vogt. 

Bruce M. Wexler, Fitzpatrick, Cella, Harper & Scinto, of New York, New York, for 

amicus curiae New York Intellectual Property Law Association. With him on the brief were 

Matthew S. Seidner and John D. Murnane. 

Rick D. Nydegger, Workman Nydegger, of Salt Lake City, Utah, for amicus curiae 

American Intellectual Property Law Association. With him on the brief was David R. Todd. 

Of counsel on the brief were Denise W. DeFranco, Foley Hoag LLP, of Boston, 

Massachusetts, and Joseph R. Re and Joseph S. Cianfrani, Knobbe Martens Olson & Bear,

of Irvine, California. 

Christopher Landau, Kirkland & Ellis LLP, of Washington, DC, for amicus curiae 

Infineon Technologies North America Corp. With him on the brief were John C. O’Quinn, of 

Washington, DC, and John M. Desmarais, Gregory S. Arovas, and Michael P. Stadnick, of 

New York, New York. 

Mark I. Levy, Kilpatrick Stockton, LLP, of Washington, DC, for amicus curiae

Association of Corporate Counsel. With him on the brief were Anthony B. Askew and 

Eugene B. Joswick, of Atlanta, Georgia. Of counsel on the brief were Frederick J. Krebs

and Susan Hackett of Washington, DC, Nelson A. Blish, Eastman Kodak, of Rochester, New 

York, John W. Hogan, Jr., Wyeth, of Madison, New Jersey, and Taraneh Maghame, Hewlett 

Packard, of Cupertino, California.

Mark A. Lemley, Keker & VanNest, LLP, of San Francisco, California, for amici curiae

Intel Corporation, et al. With him on the brief were Brian L. Ferrall and Ryan M. Kent. 

3
Erik Paul Belt, Bromberg and Sunstein LLP, of Boston, Massachusetts, for amicus

curiae Boston Patent Law Association. Of counsel on the brief was Peter Corless, Edwards 

and Angell LLP, of Boston, Massachusetts. 

Susan M. Dadio, Burns, Doane, Swecker & Mathis, L.L.P., of Alexandria, Virginia, for 

amicus curiae Bar Association of the District of Columbia – Patent, Trademark & Copyright

Section. Of counsel on the brief was Lynn E. Eccleston, The Eccleston Law Firm, of

Washington, DC. 

W. Thomas McGough, Jr., Reed Smith LLP, of Pittsburgh, Pennsylvania, for amicus

curiae Medrad, Inc. With him on the brief were Frederick H. Colen and Barry J. Coyne. Of

counsel on the brief was Gregory L. Bradley, Medrad, Inc., of Indianola, Pennsylvania. 

Peter A. Sullivan, Hughes Hubbard & Reed LLP, of New York, New York, for amicus 

curiae The Association of the Bar of the City of New York. Of counsel on the brief was

Catriona M. Collins, Cowan, Liebowitz & Latman, P.C., of New York, New York. 

Anthony R. Zeuli, Merchant & Gould P.C., of Minneapolis, Minnesota, for amicus

curiae Association of Patent Law Firms. With him on the brief were Thomas J. Leach, III

and Rachel Clark-Hughey. Of counsel on the brief were Scott P. McBride and Christopher 

R. Carroll, McAndrews, Held & Malloy Ltd., of Chicago, Illinois, and Eric R. Moran, 

McDonnell, Boehnen, Hulbert & Berghoff LLP, of Chicago, Illinois. 

Daniel B. Ravicher, Public Patent Foundation, of New York, New York, for amicus

curiae Public Patent Foundation. 

Theodore T. Herhold, Townsend and Townsend and Crew LLP, of Palo Alto,

California, for amici curiae VISA U.S.A. Inc., et al. With him on the brief were Daniel J.

Furniss, Susan M. Spaeth, Madison C. Jellins, and Mark G. Sandbaken. 

Mark A. Goldstein, SoCal IP Law Group, of Westlake Village, California, for amicus

curiae Conejo Valley Bar Association. With him on the brief were Steven C. Sereboff and 

Joel G. Landau. 

Robert J. Grey, Jr., President, American Bar Association, of Chicago, Illinois, for 

amicus curiae American Bar Association. With him on the brief was William L. LaFuze. Of 

counsel on the brief were Donald R. Dunner and Richard L. Rainey, Finnegan, Henderson,

Farabow, Garrett & Dunner, L.L.P., of Washington, DC. 

R. Polk Wagner, University of Pennsylvania Law School, of Philadelphia, 

Pennsylvania, for amicus curiae Patent Law Professors R. Polk Wagner, et al. 

Joshua D. Sarnoff, Washington College of Law, American University, of Washington, 

DC, for amici curiae Consumers Union, et al. 

4
Laura M. Slenzak, Siemens Corporation, of Auburn Hills, Michigan, for amicus curiae

The State Bar of Michigan, Intellectual Property Law Section, joined in the brief of the New 

York Intellectual Property Law Association. 

Lea Hall Speed, Baker, Donelson, Bearman & Caldwell, of Memphis, Tennessee, for 

amicus curiae Tennessee Bar Association, joined in the brief of the New York Intellectual 

Property Law Association. 

Appealed from: United States District Court for the District of Colorado 

Judge Marcia S. Krieger 

5
United States Court of Appeals for the Federal Circuit

03-1269, -1286 

EDWARD H. PHILLIPS, 

Plaintiff-Appellant, 

v. 

AWH CORPORATION, 

HOPEMAN BROTHERS, INC., and LOFTON CORPORATION, 

 Defendants-Cross Appellants. 

___________________________ 

DECIDED: July 12, 2005 

___________________________ 

Before MICHEL, Chief Judge, NEWMAN, MAYER, LOURIE, CLEVENGER, RADER, 

SCHALL, BRYSON, GAJARSA, LINN, DYK, and PROST, Circuit Judges. 

Opinion for the court filed by Circuit Judge BRYSON, in which Chief Judge MICHEL and 

Circuit Judges CLEVENGER, RADER, SCHALL, GAJARSA, LINN, DYK, and PROST 

join; and in which Circuit Judge LOURIE joins with respect to parts I, II, III, V, and VI; 

and in which Circuit Judge NEWMAN joins with respect to parts I, II, III, and V. Opinion 

concurring in part and dissenting in part filed by Circuit Judge LOURIE, in which Circuit 

Judge NEWMAN joins. Dissenting opinion filed by Circuit Judge MAYER, in which 

Circuit Judge NEWMAN joins. 

BRYSON, Circuit Judge. 

 Edward H. Phillips invented modular, steel-shell panels that can be welded 

together to form vandalism-resistant walls. The panels are especially useful in building 

prisons because they are load-bearing and impact-resistant, while also insulating 

against fire and noise. Mr. Phillips obtained a patent on the invention, U.S. Patent No. 

4,677,798 (“the ’798 patent”), and he subsequently entered into an arrangement with 
03-1269, -1286 2 

AWH Corporation, Hopeman Brothers, Inc., and Lofton Corporation (collectively “AWH”) 

to market and sell the panels. That arrangement ended in 1990. In 1991, however, Mr. 

Phillips received a sales brochure from AWH that suggested to him that AWH was 

continuing to use his trade secrets and patented technology without his consent. In a 

series of letters in 1991 and 1992, Mr. Phillips accused AWH of patent infringement and 

trade secret misappropriation. Correspondence between the parties regarding the 

matter ceased after that time. 

 In February 1997, Mr. Phillips brought suit in the United States District Court for 

the District of Colorado charging AWH with misappropriation of trade secrets and 

infringement of claims 1, 21, 22, 24, 25, and 26 of the ’798 patent. Phillips v. AWH 

Corp., No. 97-N-212 (D. Colo.). The district court dismissed the trade secret 

misappropriation claim as barred by Colorado’s three-year statute of limitations. 

With regard to the patent infringement issue, the district court focused on the 

language of claim 1, which recites “further means disposed inside the shell for 

increasing its load bearing capacity comprising internal steel baffles extending inwardly 

from the steel shell walls.” The court interpreted that language as “a means . . . for 

performing a specified function,” subject to 35 U.S.C. § 112, paragraph 6, which 

provides that such a claim “shall be construed to cover the corresponding structure, 

material, or acts described in the specification and equivalents thereof.” Looking to the 

specification of the ’798 patent, the court noted that “every textual reference in the 

Specification and its diagrams show baffle deployment at an angle other than 90° to the 

wall faces” and that “placement of the baffles at such angles creates an intermediate 

interlocking, but not solid, internal barrier.” The district court therefore ruled that, for 
03-1269, -1286 3 

purposes of the ’798 patent, a baffle must “extend inward from the steel shell walls at an 

oblique or acute angle to the wall face” and must form part of an interlocking barrier in 

the interior of the wall module. Because Mr. Phillips could not prove infringement under 

that claim construction, the district court granted summary judgment of noninfringement. 

Mr. Phillips appealed with respect to both the trade secret and patent 

infringement claims. A panel of this court affirmed on both issues. Phillips v. AWH 

Corp., 363 F.3d 1207 (Fed. Cir. 2004). As to the trade secret claim, the panel 

unanimously upheld the district court’s ruling that the claim was barred by the applicable 

statute of limitations. Id. at 1215. As to the patent infringement claims, the panel was 

divided. The majority sustained the district court’s summary judgment of 

noninfringement, although on different grounds. The dissenting judge would have 

reversed the summary judgment of noninfringement.

The panel first determined that because the asserted claims of the ’798 patent 

contain a sufficient recitation of structure, the district court erred by construing the term 

“baffles” to invoke the “means-plus-function” claim format authorized by section 112, 

paragraph 6. Id. at 1212. Nonetheless, the panel concluded that the patent uses the 

term “baffles” in a restrictive manner. Based on the patent’s written description, the 

panel held that the claim term “baffles” excludes structures that extend at a 90 degree 

angle from the walls. The panel noted that the specification repeatedly refers to the 

ability of the claimed baffles to deflect projectiles and that it describes the baffles as 

being “disposed at such angles that bullets which might penetrate the outer steel panels 

are deflected.” ’798 patent, col. 2, ll. 13-15; see also id. at col. 5, ll. 17-19 (baffles are 

“disposed at angles which tend to deflect the bullets”). In addition, the panel observed 
03-1269, -1286 4 

that nowhere in the patent is there any disclosure of a baffle projecting from the wall at a 

right angle and that baffles oriented at 90 degrees to the wall were found in the prior art. 

Based on “the specification’s explicit descriptions,” the panel concluded “that the 

patentee regarded his invention as panels providing impact or projectile resistance and 

that the baffles must be oriented at angles other than 90°.” Phillips, 363 F.3d at 1213. 

The panel added that the patent specification “is intended to support and inform the 

claims, and here it makes it unmistakably clear that the invention involves baffles angled 

at other than 90°.” Id. at 1214. The panel therefore upheld the district court’s summary 

judgment of noninfringement. 

The dissenting judge argued that the panel had improperly limited the claims to 

the particular embodiment of the invention disclosed in the specification, rather than 

adopting the “plain meaning” of the term “baffles.” The dissenting judge noted that the 

parties had stipulated that “baffles” are a “means for obstructing, impeding, or checking 

the flow of something,” and that the panel majority had agreed that the ordinary 

meaning of baffles is “something for deflecting, checking, or otherwise regulating flow.” 

Phillips, 363 F.3d at 1216-17. In the dissent’s view, nothing in the specification 

redefined the term “baffles” or constituted a disclaimer specifically limiting the term to 

less than the full scope of its ordinary meaning. Instead, the dissenting judge 

contended, the specification “merely identifies impact resistance as one of several 

objectives of the invention.” Id. at 1217. In sum, the dissent concluded that “there is no 

reason to supplement the plain meaning of the claim language with a limitation from the 

preferred embodiment.” Id. at 1218. Consequently, the dissenting judge argued that 

the court should have adopted the general purpose dictionary definition of the term 
03-1269, -1286 5 

baffle, i.e., “something for deflecting, checking, or otherwise regulating flow,” id., and 

therefore should have reversed the summary judgment of noninfringement. 

This court agreed to rehear the appeal en banc and vacated the judgment of the 

panel. Phillips v. AWH Corp., 376 F.3d 1382 (Fed. Cir. 2004). We now affirm the 

portion of the district court’s judgment addressed to the trade secret misappropriation 

claims. However, we reverse the portion of the court’s judgment addressed to the issue 

of infringement. 

I 

 Claim 1 of the ’798 patent is representative of the asserted claims with respect to 

the use of the term “baffles.” It recites: 

Building modules adapted to fit together for construction of fire, sound and 

impact resistant security barriers and rooms for use in securing records 

and persons, comprising in combination, an outer shell . . . , sealant 

means . . . and further means disposed inside the shell for increasing its 

load bearing capacity comprising internal steel baffles extending inwardly 

from the steel shell walls. 

As a preliminary matter, we agree with the panel that the term “baffles” is not 

means-plus-function language that invokes 35 U.S.C. § 112, paragraph 6. To be sure, 

the claim refers to “means disposed inside the shell for increasing its load bearing 

capacity,” a formulation that would ordinarily be regarded as invoking the means-plusfunction claim format. However, the claim specifically identifies “internal steel baffles” 

as structure that performs the recited function of increasing the shell’s load-bearing 

capacity. In contrast to the “load bearing means” limitation, the reference to “baffles” 

does not use the word “means,” and we have held that the absence of that term creates 

a rebuttable presumption that section 112, paragraph 6, does not apply. See
03-1269, -1286 6 

Personalized Media Communications, LLC v. Int’l Trade Comm’n, 161 F.3d 696, 703-04 

(Fed. Cir. 1998). 

 Means-plus-function claiming applies only to purely functional limitations that do 

not provide the structure that performs the recited function. See Watts v. XL Sys., Inc., 

232 F.3d 877, 880-81 (Fed. Cir. 2000). While the baffles in the ’798 patent are clearly 

intended to perform several functions, the term “baffles” is nonetheless structural; it is 

not a purely functional placeholder in which structure is filled in by the specification. 

See TurboCare Div. of Demag Delaval Turbomachinery Corp. v. Gen. Elec. Co., 264 

F.3d 1111, 1121 (Fed. Cir. 2001) (reasoning that nothing in the specification or 

prosecution history suggests that the patentee used the term “compressed spring” to 

denote any structure that is capable of performing the specified function); Greenberg v. 

Ethicon Endo-Surgery, Inc., 91 F.3d 1580, 1583 (Fed. Cir. 1996) (construing the term 

“detent mechanism” to refer to particular structure, even though the term has functional 

connotations). The claims and the specification unmistakably establish that the “steel 

baffles” refer to particular physical apparatus. The claim characterizes the baffles as 

“extend[ing] inwardly” from the steel shell walls, which plainly implies that the baffles are 

structures. The specification likewise makes clear that the term “steel baffles” refers to 

particular internal wall structures and is not simply a general description of any structure 

that will perform a particular function. See, e.g., ’798 patent, col. 4, ll. 25-26 (“the load 

bearing baffles 16 are optionally used with longer panels”); id., col. 4, ll. 49-50 (opposing 

panels are “compressed between the flange 35 and the baffle 26”). Because the term 

“baffles” is not subject to section 112, paragraph 6, we agree with the panel that the 

district court erred by limiting the term to corresponding structures disclosed in the 
03-1269, -1286 7 

specification and their equivalents. Accordingly, we must determine the correct 

construction of the structural term “baffles,” as used in the ’798 patent. 

II 

The first paragraph of section 112 of the Patent Act, 35 U.S.C. § 112, states that 

the specification 

shall contain a written description of the invention, and of the manner and 

process of making and using it, in such full, clear, concise, and exact 

terms as to enable any person skilled in the art to which it pertains . . . to 

make and use the same . . . . 

 The second paragraph of section 112 provides that the specification 

shall conclude with one or more claims particularly pointing out and 

distinctly claiming the subject matter which the applicant regards as his 

invention. 

Those two paragraphs of section 112 frame the issue of claim interpretation for 

us. The second paragraph requires us to look to the language of the claims to 

determine what “the applicant regards as his invention.” On the other hand, the first 

paragraph requires that the specification describe the invention set forth in the claims. 

The principal question that this case presents to us is the extent to which we should 

resort to and rely on a patent’s specification in seeking to ascertain the proper scope of 

its claims. 

This is hardly a new question. The role of the specification in claim construction 

has been an issue in patent law decisions in this country for nearly two centuries. We 

addressed the relationship between the specification and the claims at some length in 

our en banc opinion in Markman v. Westview Instruments, Inc., 52 F.3d 967, 979-81 

(Fed. Cir. 1995) (en banc), aff’d, 517 U.S. 370 (1996). We again summarized the 

applicable principles in Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576 (Fed. Cir. 
03-1269, -1286 8 

1996), and more recently in Innova/Pure Water, Inc. v. Safari Water Filtration Systems, 

Inc., 381 F.3d 1111 (Fed. Cir. 2004). What we said in those cases bears restating, for 

the basic principles of claim construction outlined there are still applicable, and we 

reaffirm them today. We have also previously considered the use of dictionaries in 

claim construction. What we have said in that regard requires clarification. 

A 

It is a “bedrock principle” of patent law that “the claims of a patent define the 

invention to which the patentee is entitled the right to exclude.” Innova, 381 F.3d at 

1115; see also Vitronics, 90 F.3d at 1582 (“we look to the words of the claims 

themselves . . . to define the scope of the patented invention”); Markman, 52 F.3d at 

980 (“The written description part of the specification itself does not delimit the right to 

exclude. That is the function and purpose of claims.”). That principle has been 

recognized since at least 1836, when Congress first required that the specification 

include a portion in which the inventor “shall particularly specify and point out the part, 

improvement, or combination, which he claims as his own invention or discovery.” Act 

of July 4, 1836, ch. 357, § 6, 5 Stat. 117, 119. In the following years, the Supreme 

Court made clear that the claims are “of primary importance, in the effort to ascertain 

precisely what it is that is patented.” Merrill v. Yeomans, 94 U.S. 568, 570 (1876). 

Because the patentee is required to “define precisely what his invention is,” the Court 

explained, it is “unjust to the public, as well as an evasion of the law, to construe it in a 

manner different from the plain import of its terms.” White v. Dunbar, 119 U.S. 47, 52 

(1886); see also Cont’l Paper Bag Co. v. E. Paper Bag Co., 210 U.S. 405, 419 (1908) 

(“the claims measure the invention”); McCarty v. Lehigh Valley R.R. Co., 160 U.S. 110, 
03-1269, -1286 9 

116 (1895) (“if we once begin to include elements not mentioned in the claim, in order to 

limit such claim . . . , we should never know where to stop”); Aro Mfg. Co. v. Convertible 

Top Replacement Co., 365 U.S. 336, 339 (1961) (“the claims made in the patent are the 

sole measure of the grant”). 

We have frequently stated that the words of a claim “are generally given their 

ordinary and customary meaning.” Vitronics, 90 F.3d at 1582; see also Toro Co. v. 

White Consol. Indus., Inc., 199 F.3d 1295, 1299 (Fed. Cir. 1999); Renishaw PLC v. 

Marposs Societa’ per Azioni, 158 F.3d 1243, 1249 (Fed. Cir. 1998). We have made 

clear, moreover, that the ordinary and customary meaning of a claim term is the 

meaning that the term would have to a person of ordinary skill in the art in question at 

the time of the invention, i.e., as of the effective filing date of the patent application. See

Innova, 381 F.3d at 1116 (“A court construing a patent claim seeks to accord a claim 

the meaning it would have to a person of ordinary skill in the art at the time of the 

invention.”); Home Diagnostics, Inc. v. LifeScan, Inc., 381 F.3d 1352, 1358 (Fed. Cir. 

2004) (“customary meaning” refers to the “customary meaning in [the] art field”); 

Ferguson Beauregard/Logic Controls v. Mega Sys., LLC, 350 F.3d 1327, 1338 (Fed. 

Cir. 2003) (claim terms “are examined through the viewing glass of a person skilled in 

the art”); see also PC Connector Solutions LLC v. SmartDisk Corp., 406 F.3d 1359, 

1363 (Fed. Cir. 2005) (meaning of claim “must be interpreted as of [the] effective filing 

date” of the patent application); Schering Corp. v. Amgen Inc., 222 F.3d 1347, 1353 

(Fed. Cir. 2000) (same). 

The inquiry into how a person of ordinary skill in the art understands a claim term 

provides an objective baseline from which to begin claim interpretation. See Innova, 
03-1269, -1286 10 

381 F.3d at 1116. That starting point is based on the well-settled understanding that 

inventors are typically persons skilled in the field of the invention and that patents are 

addressed to and intended to be read by others of skill in the pertinent art. See Verve, 

LLC v. Crane Cams, Inc., 311 F.3d 1116, 1119 (Fed. Cir. 2002) (patent documents are 

meant to be “a concise statement for persons in the field”); In re Nelson, 280 F.2d 172, 

181 (CCPA 1960) (“The descriptions in patents are not addressed to the public 

generally, to lawyers or to judges, but, as section 112 says, to those skilled in the art to 

which the invention pertains or with which it is most nearly connected.”). 

Importantly, the person of ordinary skill in the art is deemed to read the claim 

term not only in the context of the particular claim in which the disputed term appears, 

but in the context of the entire patent, including the specification. This court explained 

that point well in Multiform Desiccants, Inc. v. Medzam, Ltd., 133 F.3d 1473, 1477 (Fed. 

Cir. 1998): 

It is the person of ordinary skill in the field of the invention through 

whose eyes the claims are construed. Such person is deemed to read the 

words used in the patent documents with an understanding of their 

meaning in the field, and to have knowledge of any special meaning and 

usage in the field. The inventor’s words that are used to describe the 

invention—the inventor’s lexicography—must be understood and 

interpreted by the court as they would be understood and interpreted by a 

person in that field of technology. Thus the court starts the 

decisionmaking process by reviewing the same resources as would that 

person, viz., the patent specification and the prosecution history. 

See also Medrad, Inc. v. MRI Devices Corp., 401 F.3d 1313, 1319 (Fed. Cir. 2005) (“We 

cannot look at the ordinary meaning of the term . . . in a vacuum. Rather, we must look 

at the ordinary meaning in the context of the written description and the prosecution 

history.”); V-Formation, Inc. v. Benetton Group SpA, 401 F.3d 1307, 1310 (Fed. Cir. 

2005) (intrinsic record “usually provides the technological and temporal context to 
03-1269, -1286 11 

enable the court to ascertain the meaning of the claim to one of ordinary skill in the art 

at the time of the invention”); Unitherm Food Sys., Inc. v. Swift-Eckrich, Inc., 375 F.3d 

1341, 1351 (Fed. Cir. 2004) (proper definition is the “definition that one of ordinary skill 

in the art could ascertain from the intrinsic evidence in the record”). 

B 

In some cases, the ordinary meaning of claim language as understood by a 

person of skill in the art may be readily apparent even to lay judges, and claim 

construction in such cases involves little more than the application of the widely 

accepted meaning of commonly understood words. See Brown v. 3M, 265 F.3d 1349, 

1352 (Fed Cir. 2001) (holding that the claims did “not require elaborate interpretation”). 

In such circumstances, general purpose dictionaries may be helpful. In many cases 

that give rise to litigation, however, determining the ordinary and customary meaning of 

the claim requires examination of terms that have a particular meaning in a field of art. 

Because the meaning of a claim term as understood by persons of skill in the art is 

often not immediately apparent, and because patentees frequently use terms 

idiosyncratically, the court looks to “those sources available to the public that show what 

a person of skill in the art would have understood disputed claim language to mean.” 

Innova, 381 F.3d at 1116. Those sources include “the words of the claims themselves, 

the remainder of the specification, the prosecution history, and extrinsic evidence 

concerning relevant scientific principles, the meaning of technical terms, and the state of 

the art.” Id.; see also Gemstar-TV Guide Int’l, Inc. v. Int’l Trade Comm’n, 383 F.3d 

1352, 1364 (Fed. Cir. 2004); Vitronics, 90 F.3d at 1582-83; Markman, 52 F.3d at 979-

80. 
03-1269, -1286 12 

1 

Quite apart from the written description and the prosecution history, the claims 

themselves provide substantial guidance as to the meaning of particular claim terms. 

See Vitronics, 90 F.3d at 1582; see also ACTV, Inc. v. Walt Disney Co., 346 F.3d 1082, 

1088 (Fed. Cir. 2003) (“the context of the surrounding words of the claim also must be 

considered in determining the ordinary and customary meaning of those terms”). 

To begin with, the context in which a term is used in the asserted claim can be 

highly instructive. To take a simple example, the claim in this case refers to “steel 

baffles,” which strongly implies that the term “baffles” does not inherently mean objects 

made of steel. This court’s cases provide numerous similar examples in which the use 

of a term within the claim provides a firm basis for construing the term. See, e.g., Mars, 

Inc. v. H.J. Heinz Co., 377 F.3d 1369, 1374 (Fed. Cir. 2004) (claim term “ingredients” 

construed in light of the use of the term “mixture” in the same claim phrase); Process 

Control Corp. v. HydReclaim Corp., 190 F.3d 1350, 1356 (Fed. Cir. 1999) (claim term 

“discharge rate” construed in light of the use of the same term in another limitation of 

the same claim). 

Other claims of the patent in question, both asserted and unasserted, can also 

be valuable sources of enlightenment as to the meaning of a claim term. Vitronics, 90 

F.3d at 1582. Because claim terms are normally used consistently throughout the 

patent, the usage of a term in one claim can often illuminate the meaning of the same 

term in other claims. See Rexnord Corp. v. Laitram Corp., 274 F.3d 1336, 1342 (Fed. 

Cir. 2001); CVI/Beta Ventures, Inc. v. Tura LP, 112 F.3d 1146, 1159 (Fed. Cir. 1997). 

Differences among claims can also be a useful guide in understanding the meaning of 
03-1269, -1286 13 

particular claim terms. See Laitram Corp. v. Rexnord, Inc., 939 F.2d 1533, 1538 (Fed. 

Cir. 1991). For example, the presence of a dependent claim that adds a particular 

limitation gives rise to a presumption that the limitation in question is not present in the 

independent claim. See Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 910 (Fed. 

Cir. 2004). 

2 

The claims, of course, do not stand alone. Rather, they are part of “a fully 

integrated written instrument,” Markman, 52 F.3d at 978, consisting principally of a 

specification that concludes with the claims. For that reason, claims “must be read in 

view of the specification, of which they are a part.” Id. at 979. As we stated in Vitronics, 

the specification “is always highly relevant to the claim construction analysis. Usually, it 

is dispositive; it is the single best guide to the meaning of a disputed term.” 90 F.3d at 

1582. 

This court and its predecessors have long emphasized the importance of the 

specification in claim construction. In Autogiro Co. of America v. United States, 384 

F.2d 391, 397-98 (Ct. Cl. 1967), the Court of Claims characterized the specification as 

“a concordance for the claims,” based on the statutory requirement that the specification 

“describe the manner and process of making and using” the patented invention. The 

Court of Customs and Patent Appeals made a similar point. See In re Fout, 675 F.2d 

297, 300 (CCPA 1982) (“Claims must always be read in light of the specification. Here, 

the specification makes plain what the appellants did and did not invent . . . .”). 

 Shortly after the creation of this court, Judge Rich wrote that “[t]he descriptive 

part of the specification aids in ascertaining the scope and meaning of the claims 
03-1269, -1286 14 

inasmuch as the words of the claims must be based on the description. The 

specification is, thus, the primary basis for construing the claims.” Standard Oil Co. v. 

Am. Cyanamid Co., 774 F.2d 448, 452 (Fed. Cir. 1985). On numerous occasions since 

then, we have reaffirmed that point, stating that “[t]he best source for understanding a 

technical term is the specification from which it arose, informed, as needed, by the 

prosecution history.” Multiform Dessicants, 133 F.3d at 1478; Metabolite Labs., Inc. v. 

Lab. Corp. of Am. Holdings, 370 F.3d 1354, 1360 (Fed. Cir. 2004) (“In most cases, the 

best source for discerning the proper context of claim terms is the patent specification 

wherein the patent applicant describes the invention.”); see also, e.g., Kinik Co. v. Int’l 

Trade Comm’n, 362 F.3d 1359, 1365 (Fed. Cir. 2004) (“The words of patent claims 

have the meaning and scope with which they are used in the specification and the 

prosecution history.”); Moba, B.V. v. Diamond Automation, Inc., 325 F.3d 1306, 1315 

(Fed. Cir. 2003) (“[T]he best indicator of claim meaning is its usage in context as 

understood by one of skill in the art at the time of invention.”). 

That principle has a long pedigree in Supreme Court decisions as well. See

Hogg v. Emerson, 47 U.S. (6 How.) 437, 482 (1848) (the specification is a “component 

part of the patent” and “is as much to be considered with the [letters patent] in 

construing them, as any paper referred to in a deed or other contract”); Bates v. Coe, 98 

U.S. 31, 38 (1878) (“in case of doubt or ambiguity it is proper in all cases to refer back 

to the descriptive portions of the specification to aid in solving the doubt or in 

ascertaining the true intent and meaning of the language employed in the claims”); 

White v. Dunbar, 119 U.S. 47, 51 (1886) (specification is appropriately resorted to “for 

the purpose of better understanding the meaning of the claim”); Schriber-Schroth Co. v. 
03-1269, -1286 15 

Cleveland Trust Co., 311 U.S. 211, 217 (1940) (“The claims of a patent are always to be 

read or interpreted in light of its specifications.”); United States v. Adams, 383 U.S. 39, 

49 (1966) (“[I]t is fundamental that claims are to be construed in the light of the 

specifications and both are to be read with a view to ascertaining the invention.”). 

The importance of the specification in claim construction derives from its 

statutory role. The close kinship between the written description and the claims is 

enforced by the statutory requirement that the specification describe the claimed 

invention in “full, clear, concise, and exact terms.” 35 U.S.C. § 112, para. 1; see

Netword, LLC v. Centraal Corp., 242 F.3d 1347, 1352 (Fed. Cir. 2001) (“The claims are 

directed to the invention that is described in the specification; they do not have meaning 

removed from the context from which they arose.”); see also Markman v. Westview 

Instruments, Inc., 517 U.S. 370, 389 (1996) (“[A claim] term can be defined only in a 

way that comports with the instrument as a whole.”). In light of the statutory directive 

that the inventor provide a “full” and “exact” description of the claimed invention, the 

specification necessarily informs the proper construction of the claims. See Merck & 

Co. v. Teva Pharms. USA, Inc., 347 F.3d 1367, 1371 (Fed. Cir. 2003) (“A fundamental 

rule of claim construction is that terms in a patent document are construed with the 

meaning with which they are presented in the patent document. Thus claims must be 

construed so as to be consistent with the specification, of which they are a part.”) 

(citations omitted). In Renishaw, this court summarized that point succinctly: 

 Ultimately, the interpretation to be given a term can only be 

determined and confirmed with a full understanding of what the inventors 

actually invented and intended to envelop with the claim. The construction 

that stays true to the claim language and most naturally aligns with the 

patent’s description of the invention will be, in the end, the correct 

construction. 
03-1269, -1286 16 

158 F.3d at 1250 (citations omitted). 

 Consistent with that general principle, our cases recognize that the specification 

may reveal a special definition given to a claim term by the patentee that differs from the 

meaning it would otherwise possess. In such cases, the inventor’s lexicography 

governs. See CCS Fitness, Inc. v. Brunswick Corp., 288 F.3d 1359, 1366 (Fed. Cir. 

2002). In other cases, the specification may reveal an intentional disclaimer, or 

disavowal, of claim scope by the inventor. In that instance as well, the inventor has 

dictated the correct claim scope, and the inventor’s intention, as expressed in the 

specification, is regarded as dispositive. See SciMed Life Sys., Inc. v. Advanced 

Cardiovascular Sys., Inc., 242 F.3d 1337, 1343-44 (Fed. Cir. 2001). 

 The pertinence of the specification to claim construction is reinforced by the 

manner in which a patent is issued. The Patent and Trademark Office (“PTO”) 

determines the scope of claims in patent applications not solely on the basis of the 

claim language, but upon giving claims their broadest reasonable construction “in light 

of the specification as it would be interpreted by one of ordinary skill in the art.” In re 

Am. Acad. of Sci. Tech. Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004). Indeed, the rules of 

the PTO require that application claims must “conform to the invention as set forth in the 

remainder of the specification and the terms and phrases used in the claims must find 

clear support or antecedent basis in the description so that the meaning of the terms in 

the claims may be ascertainable by reference to the description.” 37 C.F.R. 

§ 1.75(d)(1). It is therefore entirely appropriate for a court, when conducting claim 

construction, to rely heavily on the written description for guidance as to the meaning of 

the claims. 
03-1269, -1286 17 

3 

In addition to consulting the specification, we have held that a court “should also 

consider the patent’s prosecution history, if it is in evidence.” Markman, 52 F.3d at 980; 

see also Graham v. John Deere Co., 383 U.S. 1, 33 (1966) (“[A]n invention is construed 

not only in the light of the claims, but also with reference to the file wrapper or 

prosecution history in the Patent Office.”). The prosecution history, which we have 

designated as part of the “intrinsic evidence,” consists of the complete record of the 

proceedings before the PTO and includes the prior art cited during the examination of 

the patent. Autogiro, 384 F.2d at 399. Like the specification, the prosecution history 

provides evidence of how the PTO and the inventor understood the patent. See

Lemelson v. Gen. Mills, Inc., 968 F.2d 1202, 1206 (Fed. Cir. 1992). Furthermore, like 

the specification, the prosecution history was created by the patentee in attempting to 

explain and obtain the patent. Yet because the prosecution history represents an 

ongoing negotiation between the PTO and the applicant, rather than the final product of 

that negotiation, it often lacks the clarity of the specification and thus is less useful for 

claim construction purposes. See Inverness Med. Switz. GmbH v. Warner Lambert Co., 

309 F.3d 1373, 1380-82 (Fed. Cir. 2002) (the ambiguity of the prosecution history made 

it less relevant to claim construction); Athletic Alternatives, Inc. v. Prince Mfg., Inc., 73 

F.3d 1573, 1580 (Fed. Cir. 1996) (the ambiguity of the prosecution history made it 

“unhelpful as an interpretive resource” for claim construction). Nonetheless, the 

prosecution history can often inform the meaning of the claim language by 

demonstrating how the inventor understood the invention and whether the inventor 

limited the invention in the course of prosecution, making the claim scope narrower than 
03-1269, -1286 18 

it would otherwise be. Vitronics, 90 F.3d at 1582-83; see also Chimie v. PPG Indus., 

Inc., 402 F.3d 1371, 1384 (Fed. Cir. 2005) (“The purpose of consulting the prosecution 

history in construing a claim is to ‘exclude any interpretation that was disclaimed during 

prosecution.’”), quoting ZMI Corp. v. Cardiac Resuscitator Corp., 844 F.2d 1576, 1580 

(Fed. Cir. 1988); Southwall Techs., Inc. v. Cardinal IG Co., 54 F.3d 1570, 1576 (Fed. 

Cir. 1995). 

C 

Although we have emphasized the importance of intrinsic evidence in claim 

construction, we have also authorized district courts to rely on extrinsic evidence, which 

“consists of all evidence external to the patent and prosecution history, including expert 

and inventor testimony, dictionaries, and learned treatises.” Markman, 52 F.3d at 980, 

citing Seymour v. Osborne, 78 U.S. (11 Wall.) 516, 546 (1870); see also Vitronics, 90 

F.3d at 1583. However, while extrinsic evidence “can shed useful light on the relevant 

art,” we have explained that it is “less significant than the intrinsic record in determining 

‘the legally operative meaning of claim language.’” C.R. Bard, Inc. v. U.S. Surgical 

Corp., 388 F.3d 858, 862 (Fed. Cir. 2004), quoting Vanderlande Indus. Nederland BV v. 

Int’l Trade Comm’n, 366 F.3d 1311, 1318 (Fed. Cir. 2004); see also Astrazeneca AB v. 

Mutual Pharm. Co., 384 F.3d 1333, 1337 (Fed. Cir. 2004). 

Within the class of extrinsic evidence, the court has observed that dictionaries 

and treatises can be useful in claim construction. See Renishaw, 158 F.3d at 1250; 

Rexnord, 274 F.3d at 1344. We have especially noted the help that technical 

dictionaries may provide to a court “to better understand the underlying technology” and 

the way in which one of skill in the art might use the claim terms. Vitronics, 90 F.3d at 
03-1269, -1286 19 

1584 n.6. Because dictionaries, and especially technical dictionaries, endeavor to 

collect the accepted meanings of terms used in various fields of science and 

technology, those resources have been properly recognized as among the many tools 

that can assist the court in determining the meaning of particular terminology to those of 

skill in the art of the invention. See Teleflex, Inc. v. Ficosa N. Am. Corp., 299 F.3d 

1313, 1325 (Fed. Cir. 2002). Such evidence, we have held, may be considered if the 

court deems it helpful in determining “the true meaning of language used in the patent 

claims.” Markman, 52 F.3d at 980. 

We have also held that extrinsic evidence in the form of expert testimony can be 

useful to a court for a variety of purposes, such as to provide background on the 

technology at issue, to explain how an invention works, to ensure that the court’s 

understanding of the technical aspects of the patent is consistent with that of a person 

of skill in the art, or to establish that a particular term in the patent or the prior art has a 

particular meaning in the pertinent field. See Pitney Bowes, Inc. v. Hewlett-Packard 

Co., 182 F.3d 1298, 1308-09 (Fed. Cir. 1999); Key Pharms. v. Hercon Labs. Corp., 161 

F.3d 709, 716 (Fed. Cir. 1998). However, conclusory, unsupported assertions by 

experts as to the definition of a claim term are not useful to a court. Similarly, a court 

should discount any expert testimony “that is clearly at odds with the claim construction 

mandated by the claims themselves, the written description, and the prosecution 

history, in other words, with the written record of the patent.” Key Pharms., 161 F.3d at 

716. 

We have viewed extrinsic evidence in general as less reliable than the patent and 

its prosecution history in determining how to read claim terms, for several reasons. 
03-1269, -1286 20 

First, extrinsic evidence by definition is not part of the patent and does not have the 

specification’s virtue of being created at the time of patent prosecution for the purpose 

of explaining the patent’s scope and meaning. Second, while claims are construed as 

they would be understood by a hypothetical person of skill in the art, extrinsic 

publications may not be written by or for skilled artisans and therefore may not reflect 

the understanding of a skilled artisan in the field of the patent. Third, extrinsic evidence 

consisting of expert reports and testimony is generated at the time of and for the 

purpose of litigation and thus can suffer from bias that is not present in intrinsic 

evidence. The effect of that bias can be exacerbated if the expert is not one of skill in 

the relevant art or if the expert’s opinion is offered in a form that is not subject to crossexamination. See Senmed, Inc. v. Richard-Allan Med. Indus., Inc., 888 F.2d 815, 819 

n.8 (Fed. Cir. 1989). Fourth, there is a virtually unbounded universe of potential 

extrinsic evidence of some marginal relevance that could be brought to bear on any 

claim construction question. In the course of litigation, each party will naturally choose 

the pieces of extrinsic evidence most favorable to its cause, leaving the court with the 

considerable task of filtering the useful extrinsic evidence from the fluff. See Daubert v. 

Merrell Dow Pharms., Inc., 509 U.S. 579, 595 (1993) (“Expert evidence can be both 

powerful and quite misleading because of the difficulty in evaluating it.”). Finally, undue 

reliance on extrinsic evidence poses the risk that it will be used to change the meaning 

of claims in derogation of the “indisputable public records consisting of the claims, the 

specification and the prosecution history,” thereby undermining the public notice 

function of patents. Southwall Techs., 54 F.3d at 1578. 
03-1269, -1286 21 

In sum, extrinsic evidence may be useful to the court, but it is unlikely to result in 

a reliable interpretation of patent claim scope unless considered in the context of the 

intrinsic evidence. Nonetheless, because extrinsic evidence can help educate the court 

regarding the field of the invention and can help the court determine what a person of 

ordinary skill in the art would understand claim terms to mean, it is permissible for the 

district court in its sound discretion to admit and use such evidence. In exercising that 

discretion, and in weighing all the evidence bearing on claim construction, the court 

should keep in mind the flaws inherent in each type of evidence and assess that 

evidence accordingly. 

III 

Although the principles outlined above have been articulated on numerous 

occasions, some of this court’s cases have suggested a somewhat different approach to 

claim construction, in which the court has given greater emphasis to dictionary 

definitions of claim terms and has assigned a less prominent role to the specification 

and the prosecution history. The leading case in this line is Texas Digital Systems, Inc. 

v. Telegenix, Inc., 308 F.3d 1193 (Fed. Cir. 2002). 

A 

In Texas Digital, the court noted that “dictionaries, encyclopedias and treatises 

are particularly useful resources to assist the court in determining the ordinary and 

customary meanings of claim terms.” 308 F.3d at 1202. Those texts, the court 

explained, are “objective resources that serve as reliable sources of information on the 

established meanings that would have been attributed to the terms of the claims by 

those of skill in the art,” and they “deserve no less fealty in the context of claim 
03-1269, -1286 22 

construction” than in any other area of law. Id. at 1203. The court added that because 

words often have multiple dictionary meanings, the intrinsic record must be consulted to 

determine which of the different possible dictionary meanings is most consistent with 

the use of the term in question by the inventor. If more than one dictionary definition is 

consistent with the use of the words in the intrinsic record, the court stated, “the claim 

terms may be construed to encompass all such consistent meanings.” Id.

The Texas Digital court further explained that the patent’s specification and 

prosecution history must be consulted to determine if the patentee has used “the words 

[of the claim] in a manner clearly inconsistent with the ordinary meaning reflected, for 

example, in a dictionary definition.” 308 F.3d at 1204. The court identified two 

circumstances in which such an inconsistency may be found. First, the court stated, 

“the presumption in favor of a dictionary definition will be overcome where the patentee, 

acting as his or her own lexicographer, has clearly set forth an explicit definition of the 

term different from its ordinary meaning.” Id. Second, “the presumption also will be 

rebutted if the inventor has disavowed or disclaimed scope of coverage, by using words 

or expressions of manifest exclusion or restriction, representing a clear disavowal of 

claim scope.” Id.

The Texas Digital court explained that it advanced the methodology set forth in 

that opinion in an effort to combat what this court has termed “one of the cardinal sins of 

patent law—reading a limitation from the written description into the claims,” SciMed 

Life Sys., 242 F.3d at 1340. The court concluded that it is improper to consult “the 

written description and prosecution history as a threshold step in the claim construction 

process, before any effort is made to discern the ordinary and customary meanings 
03-1269, -1286 23 

attributed to the words themselves.” Texas Digital, 308 F.3d at 1204. To do so, the 

court reasoned, “invites a violation of our precedent counseling against importing 

limitations into the claims.” Id. Summarizing its analysis, the Texas Digital court stated: 

By examining relevant dictionaries, encyclopedias, and treatises to 

ascertain possible meanings that would have been attributed to the words 

of the claims by those skilled in the art, and by further utilizing the intrinsic 

record to select from those possible meanings the one or ones most 

consistent with the use of the words by the inventor, the full breadth of the 

limitations intended by the inventor will be more accurately determined 

and the improper importation of unintended limitations from the written 

description into the claims will be more easily avoided. 

Id. at 1205. 

B 

Although the concern expressed by the court in Texas Digital was valid, the 

methodology it adopted placed too much reliance on extrinsic sources such as 

dictionaries, treatises, and encyclopedias and too little on intrinsic sources, in particular 

the specification and prosecution history. While the court noted that the specification 

must be consulted in every case, it suggested a methodology for claim interpretation in 

which the specification should be consulted only after a determination is made, whether 

based on a dictionary, treatise, or other source, as to the ordinary meaning or meanings 

of the claim term in dispute. Even then, recourse to the specification is limited to 

determining whether the specification excludes one of the meanings derived from the 

dictionary, whether the presumption in favor of the dictionary definition of the claim term 

has been overcome by “an explicit definition of the term different from its ordinary 

meaning,” or whether the inventor “has disavowed or disclaimed scope of coverage, by 

using words or expressions of manifest exclusion or restriction, representing a clear 

disavowal of claim scope.” 308 F.3d at 1204. In effect, the Texas Digital approach 
03-1269, -1286 24 

limits the role of the specification in claim construction to serving as a check on the 

dictionary meaning of a claim term if the specification requires the court to conclude that 

fewer than all the dictionary definitions apply, or if the specification contains a 

sufficiently specific alternative definition or disavowal. See, e.g., Texas Digital, 308 F.3d 

at 1202 (“unless compelled otherwise, a court will give a claim term the full range of its 

ordinary meaning”); Nystrom v. TREX Co., 374 F.3d 1105, 1111-13 (Fed. Cir. 2004) 

(ascertaining the “full range” of the ordinary meaning of the term “board” through a 

collection of dictionary definitions, and stating that those candidate definitions should be 

removed from consideration only if they were “disclaimed” in the written description or 

prosecution history); Inverness Med. Switz., 309 F.3d at 1379 (claim should be 

construed to encompass multiple dictionary meanings unless “the specification or 

prosecution history clearly demonstrates that only one of the multiple meanings was 

intended”). That approach, in our view, improperly restricts the role of the specification 

in claim construction. 

Assigning such a limited role to the specification, and in particular requiring that 

any definition of claim language in the specification be express, is inconsistent with our 

rulings that the specification is “the single best guide to the meaning of a disputed term,” 

and that the specification “acts as a dictionary when it expressly defines terms used in 

the claims or when it defines terms by implication.” Vitronics, 90 F.3d at 1582; Irdeto 

Access, Inc. v. Echostar Satellite Corp., 383 F.3d 1295, 1300 (Fed. Cir. 2004) (“Even 

when guidance is not provided in explicit definitional format, the specification may define 

claim terms by implication such that the meaning may be found in or ascertained by a 

reading of the patent documents.”) (citations omitted); Novartis Pharms. Corp. v. Abbott 
03-1269, -1286 25 

Labs., 375 F.3d 1328, 1334-35 (Fed. Cir. 2004) (same); Bell Atl. Network Servs., Inc. v. 

Covad Communications Group, Inc., 262 F.3d 1258, 1268 (Fed. Cir. 2001) (“[A] claim 

term may be clearly redefined without an explicit statement of redefinition.”). 

The main problem with elevating the dictionary to such prominence is that it 

focuses the inquiry on the abstract meaning of words rather than on the meaning of 

claim terms within the context of the patent. Properly viewed, the “ordinary meaning” of 

a claim term is its meaning to the ordinary artisan after reading the entire patent. Yet 

heavy reliance on the dictionary divorced from the intrinsic evidence risks transforming 

the meaning of the claim term to the artisan into the meaning of the term in the abstract, 

out of its particular context, which is the specification. The patent system is based on 

the proposition that claims cover only the invented subject matter. As the Supreme 

Court has stated, “[i]t seems to us that nothing can be more just and fair, both to the 

patentee and the public, than that the former should understand, and correctly describe, 

just what he has invented, and for what he claims a patent.” Merrill v. Yeomans, 94 

U.S. at 573-74. The use of a dictionary definition can conflict with that directive 

because the patent applicant did not create the dictionary to describe the invention. 

Thus, there may be a disconnect between the patentee’s responsibility to describe and 

claim his invention, and the dictionary editors’ objective of aggregating all possible 

definitions for particular words. 

Although the Texas Digital line of cases permit the dictionary definition to be 

narrowed in some circumstances even when there is not an explicit disclaimer or 

redefinition in the specification, too often that line of cases has been improperly relied 

upon to condone the adoption of a dictionary definition entirely divorced from the 
03-1269, -1286 26 

context of the written description. The problem is that if the district court starts with the 

broad dictionary definition in every case and fails to fully appreciate how the 

specification implicitly limits that definition, the error will systematically cause the 

construction of the claim to be unduly expansive. The risk of systematic overbreadth is 

greatly reduced if the court instead focuses at the outset on how the patentee used the 

claim term in the claims, specification, and prosecution history, rather than starting with 

a broad definition and whittling it down. 

Dictionaries, by their nature, provide an expansive array of definitions. General 

dictionaries, in particular, strive to collect all uses of particular words, from the common 

to the obscure. By design, general dictionaries collect the definitions of a term as used 

not only in a particular art field, but in many different settings. In such circumstances, it 

is inevitable that the multiple dictionary definitions for a term will extend beyond the 

“construction of the patent [that] is confirmed by the avowed understanding of the 

patentee, expressed by him, or on his behalf, when his application for the original patent 

was pending.” Goodyear Dental Vulcanite Co. v. Davis, 102 U.S. 222, 227 (1880). 

Thus, the use of the dictionary may extend patent protection beyond what should 

properly be afforded by the inventor’s patent. See Smith v. Snow, 294 U.S. 1, 14 (1935) 

(“if the claim were fairly susceptible of two constructions, that should be adopted which 

will secure to the patentee his actual invention”) (emphasis added). For that reason, we 

have stated that “a general-usage dictionary cannot overcome art-specific evidence of 

the meaning” of a claim term. Vanderlande Indus. Nederland, 366 F.3d at 1321; see 

also Renishaw, 158 F.3d at 1250, quoting Liebscher v. Boothroyd, 258 F.2d 948, 951 

(CCPA 1958) (“Indiscriminate reliance on definitions found in dictionaries can often 
03-1269, -1286 27 

produce absurd results. . . . One need not arbitrarily pick and choose from the various 

accepted definitions of a word to decide which meaning was intended as the word is 

used in a given claim. The subject matter, the context, etc., will more often than not 

lead to the correct conclusion.”). 

Even technical dictionaries or treatises, under certain circumstances, may suffer 

from some of these deficiencies. There is no guarantee that a term is used in the same 

way in a treatise as it would be by the patentee. In fact, discrepancies between the 

patent and treatises are apt to be common because the patent by its nature describes 

something novel. See Autogiro, 384 F.2d at 397 (“Often the invention is novel and 

words do not exist to describe it. The dictionary does not always keep abreast of the 

inventor. It cannot.”). 

 Moreover, different dictionaries may contain somewhat different sets of 

definitions for the same words. A claim should not rise or fall based upon the 

preferences of a particular dictionary editor, or the court’s independent decision, 

uninformed by the specification, to rely on one dictionary rather than another. Finally, 

the authors of dictionaries or treatises may simplify ideas to communicate them most 

effectively to the public and may thus choose a meaning that is not pertinent to the 

understanding of particular claim language. See generally Ellen P. Aprill, The Law of 

the Word: Dictionary Shopping in the Supreme Court, 30 Ariz. St. L.J. 275, 293-314 

(1998). The resulting definitions therefore do not necessarily reflect the inventor’s goal 

of distinctly setting forth his invention as a person of ordinary skill in that particular art 

would understand it. 
03-1269, -1286 28 

As we have noted above, however, we do not intend to preclude the appropriate 

use of dictionaries. Dictionaries or comparable sources are often useful to assist in 

understanding the commonly understood meaning of words and have been used both 

by our court and the Supreme Court in claim interpretation. See Exhibit Supply Co. v. 

Ace Patents Corp., 315 U.S. 126, 134 (1942) (relying on dictionaries to construe the 

claim term “embedded”); Weber Elec. Co. v. E.H. Freeman Elec. Co., 256 U.S. 668, 678 

(1921) (approving circuit court’s use of dictionary definitions to define claim terms); 

Renishaw, 158 F.3d at 1247-53 (approving the use of dictionaries with proper respect 

for the role of intrinsic evidence). A dictionary definition has the value of being an 

unbiased source “accessible to the public in advance of litigation.” Vitronics, 90 F.3d at 

1585. As we said in Vitronics, judges are free to consult dictionaries and technical 

treatises 

at any time in order to better understand the underlying technology and 

may also rely on dictionary definitions when construing claim terms, so 

long as the dictionary definition does contradict any definition found in or 

ascertained by a reading of the patent documents. 

Id. at 1584 n.6. 

We also acknowledge that the purpose underlying the Texas Digital line of 

cases—to avoid the danger of reading limitations from the specification into the claim—

is sound. Moreover, we recognize that the distinction between using the specification to 

interpret the meaning of a claim and importing limitations from the specification into the 

claim can be a difficult one to apply in practice. See Comark Communications, Inc. v. 

Harris Corp., 156 F.3d 1182, 1186-87 (Fed. Cir. 1998) (“there is sometimes a fine line 

between reading a claim in light of the specification, and reading a limitation into the 

claim from the specification”). However, the line between construing terms and 
03-1269, -1286 29 

importing limitations can be discerned with reasonable certainty and predictability if the 

court’s focus remains on understanding how a person of ordinary skill in the art would 

understand the claim terms. For instance, although the specification often describes 

very specific embodiments of the invention, we have repeatedly warned against 

confining the claims to those embodiments. See, e.g., Nazomi Communications, Inc. v. 

ARM Holdings, PLC, 403 F.3d 1364, 1369 (Fed. Cir. 2005) (claims may embrace 

“different subject matter than is illustrated in the specific embodiments in the 

specification”); Liebel-Flarsheim, 358 F.3d at 906-08; Teleflex, 299 F.3d at 1327; SRI 

Int’l v. Matsushita Elec. Corp. of Am., 775 F.2d 1107, 1121 (Fed. Cir. 1985). In 

particular, we have expressly rejected the contention that if a patent describes only a 

single embodiment, the claims of the patent must be construed as being limited to that 

embodiment. Gemstar-TV Guide, 383 F.3d at 1366. That is not just because section 

112 of the Patent Act requires that the claims themselves set forth the limits of the 

patent grant, but also because persons of ordinary skill in the art rarely would confine 

their definitions of terms to the exact representations depicted in the embodiments. 

To avoid importing limitations from the specification into the claims, it is important 

to keep in mind that the purposes of the specification are to teach and enable those of 

skill in the art to make and use the invention and to provide a best mode for doing so. 

See Spectra-Physics, Inc. v. Coherent, Inc., 827 F.2d 1524, 1533 (Fed. Cir. 1987). One 

of the best ways to teach a person of ordinary skill in the art how to make and use the 

invention is to provide an example of how to practice the invention in a particular case. 

Much of the time, upon reading the specification in that context, it will become clear 

whether the patentee is setting out specific examples of the invention to accomplish 
03-1269, -1286 30 

those goals, or whether the patentee instead intends for the claims and the 

embodiments in the specification to be strictly coextensive. See SciMed Life Sys., 242 

F.3d at 1341. The manner in which the patentee uses a term within the specification 

and claims usually will make the distinction apparent. See Snow v. Lake Shore & M.S. 

Ry. Co., 121 U.S. 617, 630 (1887) (it was clear from the specification that there was 

“nothing in the context to indicate that the patentee contemplated any alternative” 

embodiment to the one presented). 

In the end, there will still remain some cases in which it will be hard to determine 

whether a person of skill in the art would understand the embodiments to define the 

outer limits of the claim term or merely to be exemplary in nature. While that task may 

present difficulties in some cases, we nonetheless believe that attempting to resolve 

that problem in the context of the particular patent is likely to capture the scope of the 

actual invention more accurately than either strictly limiting the scope of the claims to 

the embodiments disclosed in the specification or divorcing the claim language from the 

specification. 

In Vitronics, this court grappled with the same problem and set forth guidelines 

for reaching the correct claim construction and not imposing improper limitations on 

claims. 90 F.3d at 1582. The underlying goal of our decision in Vitronics was to 

increase the likelihood that a court will comprehend how a person of ordinary skill in the 

art would understand the claim terms. See id. at 1584. In that process, we recognized 

that there is no magic formula or catechism for conducting claim construction. Nor is 

the court barred from considering any particular sources or required to analyze sources 

in any specific sequence, as long as those sources are not used to contradict claim 
03-1269, -1286 31 

meaning that is unambiguous in light of the intrinsic evidence. See id. at 1583-84; Intel 

Corp. v. VIA Techs., Inc., 319 F.3d 1357, 1367 (Fed. Cir. 2003). For example, a judge 

who encounters a claim term while reading a patent might consult a general purpose or 

specialized dictionary to begin to understand the meaning of the term, before reviewing 

the remainder of the patent to determine how the patentee has used the term. The 

sequence of steps used by the judge in consulting various sources is not important; 

what matters is for the court to attach the appropriate weight to be assigned to those 

sources in light of the statutes and policies that inform patent law. Vitronics, 90 F.3d at 

1582. In Vitronics, we did not attempt to provide a rigid algorithm for claim construction, 

but simply attempted to explain why, in general, certain types of evidence are more 

valuable than others. Today, we adhere to that approach and reaffirm the approach to 

claim construction outlined in that case, in Markman, and in Innova. We now turn to the 

application of those principles to the case at bar. 

IV 

A 

 The critical language of claim 1 of the ’798 patent—“further means disposed 

inside the shell for increasing its load bearing capacity comprising internal steel baffles 

extending inwardly from the steel shell walls”—imposes three clear requirements with 

respect to the baffles. First, the baffles must be made of steel. Second, they must be 

part of the load-bearing means for the wall section. Third, they must be pointed inward 

from the walls. Both parties, stipulating to a dictionary definition, also conceded that the 

term “baffles” refers to objects that check, impede, or obstruct the flow of something. 
03-1269, -1286 32 

The intrinsic evidence confirms that a person of skill in the art would understand that the 

term “baffles,” as used in the ’798 patent, would have that generic meaning. 

 The other claims of the ’798 patent specify particular functions to be served by 

the baffles. For example, dependent claim 2 states that the baffles may be “oriented 

with the panel sections disposed at angles for deflecting projectiles such as bullets able 

to penetrate the steel plates.” The inclusion of such a specific limitation on the term 

“baffles” in claim 2 makes it likely that the patentee did not contemplate that the term 

“baffles” already contained that limitation. See Dow Chem. Co. v. United States, 226 

F.3d 1334, 1341-42 (Fed. Cir. 2000) (concluding that an independent claim should be 

given broader scope than a dependent claim to avoid rendering the dependent claim 

redundant). Independent claim 17 further supports that proposition. It states that 

baffles are placed “projecting inwardly from the outer shell at angles tending to deflect 

projectiles that penetrate the outer shell.” That limitation would be unnecessary if 

persons of skill in the art understood that the baffles inherently served such a function. 

See TurboCare, 264 F.3d at 1123 (claim terms should not be read to contain a limitation 

“where another claim restricts the invention in exactly the [same] manner”). Dependent 

claim 6 provides an additional requirement for the baffles, stating that “the internal 

baffles of both outer panel sections overlap and interlock at angles providing deflector 

panels extending from one end of the module to the other.” If the baffles recited in claim 

1 were inherently placed at specific angles, or interlocked to form an intermediate 

barrier, claim 6 would be redundant. 

 The specification further supports the conclusion that persons of ordinary skill in 

the art would understand the baffles recited in the ’798 patent to be load-bearing objects 
03-1269, -1286 33 

that serve to check, impede, or obstruct flow. At several points, the specification 

discusses positioning the baffles so as to deflect projectiles. See ’798 patent, col. 2, ll. 

13-15; id., col. 5, ll. 17-19. The patent states that one advantage of the invention over 

the prior art is that “[t]here have not been effective ways of dealing with these powerful 

impact weapons with inexpensive housing.” Id., col. 3, ll. 28-30. While that statement 

makes clear the invention envisions baffles that serve that function, it does not imply 

that in order to qualify as baffles within the meaning of the claims, the internal support 

structures must serve the projectile-deflecting function in all the embodiments of all the 

claims. The specification must teach and enable all the claims, and the section of the 

written description discussing the use of baffles to deflect projectiles serves that 

purpose for claims 2, 6, 17, and 23, which specifically claim baffles that deflect 

projectiles. See In re Wright, 999 F.2d 1557, 1561 (Fed. Cir. 1993). 

The specification discusses several other purposes served by the baffles. For 

example, the baffles are described as providing structural support. The patent states 

that one way to increase load-bearing capacity is to use “at least in part inwardly 

directed steel baffles 15, 16.” ’798 patent, col. 4, ll. 14-15. The baffle 16 is described 

as a “strengthening triangular baffle.” Id., col. 4, line 37. Importantly, Figures 4 and 6 

do not show the baffles as part of an “intermediate interlocking, but not solid, internal 

barrier.” In those figures, the baffle 16 simply provides structural support for one of the 

walls, as depicted below: 
Other uses for the baffles are listed in the specification as well. In Figure 7, the 

overlapping flanges “provide for overlapping and interlocking the baffles to produce 

substantially an intermediate barrier wall between the opposite [wall] faces”: 

 

’798 patent, col. 5, ll. 26-29. Those baffles thus create small compartments that can be 

filled with either sound and thermal insulation or rock and gravel to stop projectiles. Id., 

03-1269, -1286 34 
03-1269, -1286 35 

col. 5, ll. 29-34. By separating the interwall area into compartments (see, e.g., 

compartment 55 in Figure 7), the user of the modules can choose different types of 

material for each compartment, so that the module can be “easily custom tailored for the 

specific needs of each installation.” Id., col. 5, ll. 36-37. When material is placed into 

the wall during installation, the baffles obstruct the flow of material from one 

compartment to another so that this “custom tailoring” is possible. 

The fact that the written description of the ’798 patent sets forth multiple 

objectives to be served by the baffles recited in the claims confirms that the term 

“baffles” should not be read restrictively to require that the baffles in each case serve all 

of the recited functions. We have held that “[t]he fact that a patent asserts that an 

invention achieves several objectives does not require that each of the claims be 

construed as limited to structures that are capable of achieving all of the objectives.” 

Liebel-Flarsheim, 358 F.3d at 908; see also Resonate Inc. v. Alteon Websystems, Inc., 

338 F.3d 1360, 1367 (Fed. Cir. 2003). Although deflecting projectiles is one of the 

advantages of the baffles of the ’798 patent, the patent does not require that the inward 

extending structures always be capable of performing that function. Accordingly, we 

conclude that a person of skill in the art would not interpret the disclosure and claims of 

the ’798 patent to mean that a structure extending inward from one of the wall faces is a 

“baffle” if it is at an acute or obtuse angle, but is not a “baffle” if it is disposed at a right 

angle. 

B 

Invoking the principle that “claims should be so construed, if possible, as to 

sustain their validity,” Rhine v. Casio, Inc., 183 F.3d 1342, 1345 (Fed Cir. 1999), AWH 
03-1269, -1286 36 

argues that the term “baffles” should be given a restrictive meaning because if the term 

is not construed restrictively, the asserted claims would be invalid. 

While we have acknowledged the maxim that claims should be construed to 

preserve their validity, we have not applied that principle broadly, and we have certainly 

not endorsed a regime in which validity analysis is a regular component of claim 

construction. See Nazomi Communications, 403 F.3d at 1368-69. Instead, we have 

limited the maxim to cases in which “the court concludes, after applying all the available 

tools of claim construction, that the claim is still ambiguous.” Liebel-Flarsheim, 358 F.3d 

at 911; see also Generation II Orthonics Inc. v. Med. Tech. Inc., 263 F.3d 1356, 1365 

(Fed. Cir. 2001) (“[C]laims can only be construed to preserve their validity where the 

proposed claim construction is ‘practicable,’ is based on sound claim construction 

principles, and does not revise or ignore the explicit language of the claims.”); Elekta 

Instrument S.A. v. O.U.R. Scientific Int’l, Inc., 214 F.3d 1302, 1309 (Fed. Cir. 2000) 

(“having concluded that the amended claim is susceptible of only one reasonable 

construction, we cannot construe the claim differently from its plain meaning in order to 

preserve its validity”); E.I. du Pont de Nemours & Co. v. Phillips Petroleum Co., 849 

F.2d 1430, 1434 (Fed. Cir. 1988) (rejecting argument that limitations should be added to 

claims to preserve the validity of the claims). In such cases, we have looked to whether 

it is reasonable to infer that the PTO would not have issued an invalid patent, and that 

the ambiguity in the claim language should therefore be resolved in a manner that 

would preserve the patent’s validity. 

That is the rationale that gave rise to the maxim in the first place. In Klein v. 

Russell, 86 U.S. (19 Wall.) 433, 466 (1873), the owner of a reissued patent argued for a 
03-1269, -1286 37 

narrow construction of the patent, while the accused infringer argued for a broader 

construction. The Court noted that the law “required that the reissue should be for the 

same invention as the original patent.” Id. Because the reissue, which was granted 

under the predecessor to 35 U.S.C. § 251, would have been improper under the 

broader construction, the Court “presumed the Commissioner did his duty” and did not 

issue an invalid patent. For that reason, among others, the Court construed the 

disputed claim language in a manner that “sustain[ed] the patent and the construction 

claimed by the patentee,” since that “can be done consistently with the language which 

he has employed.” Id. The applicability of the doctrine in a particular case therefore 

depends on the strength of the inference that the PTO would have recognized that one 

claim interpretation would render the claim invalid, and that the PTO would not have 

issued the patent assuming that to be the proper construction of the term. 

In this case, unlike in Klein and other cases in which the doctrine of construing 

claims to preserve their validity has been invoked, the claim term at issue is not 

ambiguous. Thus, it can be construed without the need to consider whether one 

possible construction would render the claim invalid while the other would not. The 

doctrine of construing claims to preserve their validity, a doctrine of limited utility in any 

event, therefore has no applicability here. 

In sum, we reject AWH’s arguments in favor of a restrictive definition of the term 

“baffles.” Because we disagree with the district court’s claim construction, we reverse 

the summary judgment of noninfringement. In light of our decision on claim 

construction, it is necessary to remand the infringement claims to the district court for 

further proceedings. 
03-1269, -1286 38 

V 

 With respect to Mr. Phillips’s allegation of misappropriation of trade secrets, we 

agree with the panel’s decision upholding the district court’s ruling on that issue, in 

which the district court dismissed the trade secret claim on statute of limitations 

grounds. See Phillips, 363 F.3d at 1214-1216. Accordingly, based on the panel’s 

disposition of that issue, we affirm the district court’s dismissal of the trade secret claim. 

With respect to AWH’s cross-appeal, we also agree with the panel’s reasoning and its 

conclusion that the cross-appeal is improper. See id. at 1216. We therefore dismiss 

the cross-appeal. 

VI 

 In our order granting rehearing en banc, we asked the parties to brief various 

questions, including the following: “Consistent with the Supreme Court’s decision in 

Markman v. Westview Instruments, 517 U.S. 370 (1996), and our en banc decision in 

Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 (Fed. Cir. 1998), is it appropriate 

for this court to accord any deference to any aspect of trial court claim construction 

rulings? If so, on what aspects, in what circumstances, and to what extent?” After 

consideration of the matter, we have decided not to address that issue at this time. We 

therefore leave undisturbed our prior en banc decision in Cybor. 

 Each party shall bear its own costs for this appeal. 

AFFIRMED IN PART, REVERSED IN PART, DISMISSED IN PART, and REMANDED.
United States Court of Appeals for the Federal Circuit 

03-1269,-1286 

EDWARD H. PHILLIPS, 

 Plaintiff-Appellant, 

v. 

AWH CORPORATION, 

HOPEMAN BROTHERS, INC., and LOFTON CORPORATION, 

 Defendants-Cross Appellants. 

LOURIE, Circuit Judge, concurring in part and dissenting in part, with whom NEWMAN, 

Circuit Judge, joins. 

I fully join the portion of the court's opinion resolving the relative weights of 

specification and dictionaries in interpreting patent claims, in favor of the specification. I 

could elaborate more expansively on that topic, but Judge Bryson's opinion for the 

majority says it so well, there is little reason for me to repeat its truths. I also agree with 

the court that claims need not necessarily be limited to specific or preferred 

embodiments in the specification, although they are limited to what is contained in the 

overall disclosure of the specification. 

 However, I do dissent from the court's decision to reverse and remand the district 

court's decision. The original panel decision of this court, which implicitly decided the 

case based on the priorities that the en banc court has now reaffirmed, interpreted the 

claims in light of the specification and found that the defendant did not infringe the 
claims. We affirmed the district court, which had arrived at a similar conclusion. The 

dissent from the panel decision relied on the "dictionaries first" procedure, which the 

court now has decided not to follow. Thus, while the claim construction issue had to be 

decided by the en banc court, I see no reason for the court, having reaffirmed the 

principle on which the district judge and the panel originally decided the case, to send it 

back for further review. 

The court premises its reverse-and-remand decision on the concept of claim

differentiation and the reasoning that the contested term "baffle" need not fulfill all of the 

functions set out for it in the specification. Reasonable people can differ on those 

points. However, the court did not take this case en banc because the full court differed 

with the panel majority on those disputable criteria. It did so to resolve the claim

construction issue, which it has now done so well. Having done so, I believe that it 

should simply affirm the district court's decision on the merits, consistently with that 

court's rationale and that of the panel that affirmed the district court, which it now 

adopts. 

I will not critique in detail particular statements the majority makes in rationalizing

its reversal of the district court's decision, such as "that a person of skill in the art would 

not interpret the disclosure and claims of the '798 patent to mean that a structure 

extending inward from one of the wall faces is a 'baffle' if it is at an acute or obtuse 

angle, but is not a 'baffle' if it is disposed at a right angle," or that "the patent does not

require that the inward extending structures always be capable of performing that

function [deflecting projectiles]" in order to be considered 'baffles'. 

03-1269,-1286 2 
I will simply point out that the specification contains no disclosure of baffles at 

right angles. Moreover, as the majority correctly states, a patent specification is

intended to describe one's invention, and it is essential to read a specification in order to 

interpret the meaning of the claims. This specification makes clear that the "baffles" in 

this invention are angled. There is no reference to baffles that show them to be other

than angled. The abstract refers to "bullet deflecting . . . baffles." Only angled baffles

can deflect. It then mentions "internal baffles at angles for deflecting bullets." That 

could not be clearer. The specification then refers several times to baffles, often to 

figures in the drawings, all of which are to angled baffles. A compelling point is that the 

only numbered references to baffles (15, 16, 26, 27, 30, and 31) all show angled baffles. 

The specification further states that steel panels "form the internal baffles at 

angles for deflecting bullets." It states that the baffles are "disposed at such angles that

bullets which might penetrate the outer steel panels are deflected." It explains that if 

bullets "were to penetrate the outer steel wall, the baffles are disposed at angles which 

tend to deflect the bullets." There is no specific reference in this patent to a baffle that is 

not angled at other than 90o. 

While, as the majority states, the specification indicates that multiple objectives 

are achieved by the invention, none of the other objectives is dependent upon whether

the baffles are at other than a 90o angle, whereas the constantly stated objective of 

deflection of bullets is dependent upon such an angle. 

Finally, even though claim construction is a question of law, reviewable by this 

court without formal deference, I do believe that we ought to lean toward affirmance of a

claim construction in the absence of a strong conviction of error. I do not have such a

03-1269,-1286 3 
conviction in this case, after considering the district court's opinion and the patent

specification. 

For these reasons, while I wholeheartedly join the majority opinion in its

discussion and resolution of the "specification v. dictionaries" issue, I would affirm the 

decision below. 

03-1269,-1286 4 
United States Court of Appeals for the Federal Circuit 

 

03-1269, -1286 

EDWARD H. PHILLIPS, 

 Plaintiff-Appellant, 

v. 

AWH CORPORATION, 

HOPEMAN BROTHERS, INC., and LOFTON CORPORATION, 

 Defendants-Cross Appellants. 

MAYER, Circuit Judge, with whom NEWMAN, Circuit Judge, joins, dissenting. 

Now more than ever I am convinced of the futility, indeed the absurdity, of this 

court’s persistence in adhering to the falsehood that claim construction is a matter of 

law devoid of any factual component. Because any attempt to fashion a coherent 

standard under this regime is pointless, as illustrated by our many failed attempts to do 

so, I dissent. 

This court was created for the purpose of bringing consistency to the patent field. 

See H.R. Rep. No. 312, 97th Cong., 1st Sess. 20-23 (1981). Instead, we have taken 

this noble mandate, to reinvigorate the patent and introduce predictability to the field, 

and focused inappropriate power in this court. In our quest to elevate our importance, 

we have, however, disregarded our role as an appellate court; the resulting mayhem 

has seriously undermined the legitimacy of the process, if not the integrity of the 

institution. 
In the name of uniformity, Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 1448 

(Fed. Cir. 1998) (en banc), held that claim construction does not involve subsidiary or 

underlying questions of fact and that we are, therefore, unbridled by either the expertise

or efforts of the district court.1

 What we have wrought, instead, is the substitution of a 

black box, as it so pejoratively has been said of the jury, with the black hole of this court. 

Out of this void we emit “legal” pronouncements by way of “interpretive necromancy”2

; 

these rulings resemble reality, if at all, only by chance. Regardless, and with a blind eye 

to the consequences, we continue to struggle under this irrational and reckless regime, 

trying every alternative—dictionaries first, dictionaries second, never dictionaries, etc., 

etc., etc. 

Again today we vainly attempt to establish standards by which this court will 

interpret claims. But after proposing no fewer than seven questions, receiving more 

than thirty amici curiae briefs, and whipping the bar into a frenzy of expectation, we say

nothing new, but merely restate what has become the practice over the last ten years—

that we will decide cases according to whatever mode or method results in the outcome 

we desire, or at least allows us a seemingly plausible way out of the case. I am not 

surprised by this. Indeed, there can be no workable standards by which this court will 

interpret claims so long as we are blind to the factual component of the task. See

 1 The Supreme Court did not suggest in affirming Markman v. Westview 

Instruments, Inc., 52 F.3d 967 (1995) (en banc), that claim construction is a purely legal

question. 517 U.S. 370 (1996). It held only that, as a policy matter, the judge, as 

opposed to the jury, should determine the meaning of a patent claim. See Cybor, 138 

F.3d at 1464 (Mayer, C.J., dissenting) (explaining that “the [Supreme] Court chose not

to accept our formulation of claim construction: as a pure question of law to be decided 

de novo in all cases on appeal”). 

2

 See The Holmes Group, Inc. v. Vornado Air Circulation Sys., Inc., 535 

U.S. 826, 833 (2002). 

03-1269,-1286 2
Cooter & Gell v. Hartmarx Corp., 496 U.S. 384, 405 (1990) (“Fact-bound resolutions

cannot be made uniform through appellate review, de novo or otherwise.” (quoting 

Mars Steel Corp. v. Cont’l Bank N.A., 880 F.2d 928, 936 (7th Cir.1989))).3

Federal Rule of Civil Procedure 52(a) states that “[f]indings of fact . . . shall not 

be set aside unless clearly erroneous, and due regard shall be given to the opportunity

of the trial court to judge of the credibility of witnesses.” According to the Supreme 

Court, this “[r]ule means what it says”—that findings of fact, even “those described as

‘ultimate facts’ because they may determine the outcome of litigation,” are to be 

reviewed deferentially on appeal.4

 Bose Corp. v. Consumers Union of United States, 

 3 The question asked but not answered by the court which might have 

allowed it to cure its self-inflicted wound was: “Question 7. Consistent with the 

Supreme Court’s decision in Markman v. Westview Instruments, Inc., 517 U.S. 370 

(1996) and our en banc decision in Cybor Corp. v. FAS Technologies, Inc., 138 F.3d 

1448 (Fed. Cir. 1998), is it appropriate for this court to accord any deference to any

aspect of trial court claim construction rulings? If so, on what aspects, in what 

circumstances, and to what extent?” 

4 Because some facts are so intertwined with a constitutional standard the 

Supreme Court has held that de novo review is appropriate. For example, whether a 

defendant has acted with actual malice in a defamation suit is reviewed de novo

because, among other reasons, the scope of the First Amendment is shaped and 

applied by reference to such factual determinations. Bose, 466 U.S. at 502 (“[T]he 

content of the rule is not revealed simply by its literal text, but rather is given meaning 

through the evolutionary process of common-law adjudication.”). Similarly, whether

there is reasonable suspicion to conduct an investigatory stop or probable cause to 

perform a search under the Fourth Amendment are reviewed without deference. 

Ornelas v. United States, 517 U.S. 690, 696 (1996) (holding that the protections 

afforded by the Fourth Amendment are “fluid concepts that take their substantive 

content from the particular contexts in which the standards are being assessed”). The 

reasoning behind these limited exceptions surely does not apply to claim construction. 

While appearing from the perspective of this court’s limited sphere of influence to be 

dreadfully important, claim construction does not implicate a constitutional value. Cf.

Bose, 466 U.S. at 502 (“[T]he constitutional values protected by the rule make it 

imperative that judges—and in some cases judges of [the Supreme] Court—make sure 

that it is correctly applied.”). This is illustrated by the fact that the outcome of a patent

case, unlike a defamation or illegal search case, has little impact on how future cases 

03-1269,-1286 3
466 U.S. 485, 498 & 501 (1984); see also Anderson v. Bessemer City, 470 U.S. 564, 

575 (1985) (“[R]eview of factual findings under the clearly-erroneous standard—with its

deference to the trier of fact—is the rule, not the exception.”); Pullman-Standard v.

United Steel Workers of Am., 456 U.S. 273, 287 (1982) (“Rule 52(a) broadly requires

that findings of fact not be set aside unless clearly erroneous.”); United States v. United

States Gypsum Co., 333 U.S. 364, 394 (1948). Even those findings of fact based 

entirely on documentary evidence are entitled to deference. Anderson, 470 U.S. at 574 

(“That [Rule 52(a)] goes on to emphasize the special deference to be paid credibility

determinations does not alter its clear command: Rule 52(a) ‘does not make exceptions

or purport to exclude certain categories of factual findings from the obligation of a court 

of appeals to accept a district court’s findings unless clearly erroneous.’” (quoting 

Pullman-Standard, 456 U.S. at 287)). In short, we are obligated by Rule 52(a) to review

the factual findings of the district court that underlie the determination of claim

construction for clear error. 

While this court may persist in the delusion that claim construction is a purely 

legal determination, unaffected by underlying facts, it is plainly not the case. Claim

construction is, or should be, made in context: a claim should be interpreted both from 

the perspective of one of ordinary skill in the art and in view of the state of the art at the

time of invention. See Multiform Desiccants, Inc. v. Medzam, Ltd., 133 F.3d 1473, 1477

 

are decided or on how future parties behave. Cf. id. at 501 n.17 (“Regarding certain 

largely factual questions in some areas of the law, the stakes—in terms of impact on 

future cases and future conduct—are too great to entrust them finally to the judgment of 

the trier of fact.”). Even if claim construction did implicate a constitutional value, it, 

unlike the decisions underlying the First and Fourth Amendments, could readily be 

reduced, when distinguished from its factual underpinnings, to “a neat set of legal rules.” 

Ornelas, 517 U.S. at 695-96 (quoting Ill. v. Gates, 462 U.S. 213, 232 (1983)). 

03-1269,-1286 4
(Fed. Cir. 1998) (“It is the person of ordinary skill in the field of the invention through 

whose eyes the claims are construed.”). These questions, which are critical to the 

correct interpretation of a claim, are inherently factual. They are hotly contested by the 

parties, not by resort to case law as one would expect for legal issues, but based on 

testimony and documentary evidence.5

 During so called Markman “hearings,” which 

are often longer than jury trials, parties battle over experts offering conflicting evidence

regarding who qualifies as one of ordinary skill in the art; the meaning of patent terms to

that person; the state of the art at the time of the invention; contradictory dictionary 

definitions and which would be consulted by the skilled artisan; the scope of specialized 

terms; the problem a patent was solving; what is related or pertinent art; whether a 

construction was disallowed during prosecution; how one of skill in the art would 

understand statements during prosecution; and on and on. In order to reconcile the 

parties’ inconsistent submissions and arrive at a sound interpretation, the district court is 

required to sift through and weigh volumes of evidence. While this court treats the 

district court as an intake clerk, whose only role is to collect, shuffle and collate 

evidence, the reality, as revealed by conventional practice, is far different. 

Even if the procedures employed by the district court did not show that it is

engaging in factfinding, the nature of the questions underlying claim construction 

illustrate that they are factual and should be reviewed in accordance with Rule 52(a). 

For each patent, for example, who qualifies as one of ordinary skill in the art will differ, 

 5 That most of the cases now appealed to this court are “summary 

judgments” is irrelevant. We have artificially renamed findings of fact as legal 

conclusions; the district courts have dutifully conformed to our fictional characterization, 

but this does not change the inherent nature of the inquiry. Of course, if the parties do 

not dispute the material facts, summary judgment is appropriate. 

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just as the state of the art at the time of invention will differ. These subsidiary

determinations are specific, multifarious and not susceptible to generalization; as such 

their resolution in one case will bear very little, if at all, on the resolution of subsequent

cases. See Ornelas, 517 U.S. at 703 (“Law clarification requires generalization, and 

some issues lend themselves to generalization much more than others.”); Pierce v. 

Underwood, 487 U.S. 552, 561-62 (1988) (“Many questions that arise in litigation are 

not amenable to regulation by rule because they involve multifarious, fleeting, special, 

narrow facts that utterly resist generalization.” (quoting Maurice Rosenberg, Judicial 

Discretion of the Trial Court, Viewed from Above, 22 Syracuse L. Rev. 635, 662 

(1971))); Icicle Seafoods, Inc. v. Worthington, 475 U.S. 709, 714 (1986) (rejecting de 

novo review of factual questions, even when outcome determinative). That the 

determination of the meaning of a particular term in one patent will not necessarily bear

on the interpretation of the same term in a subsequent patent illustrates this point; while

the term is the same, the underlying factual context is different. It further proves that 

these questions (e.g., who qualifies as one of ordinary skill in the art and what was the

state of the art at the time of invention, among others) are implicitly being determined in 

each case; because we refuse to acknowledge either their existence or importance, 

however, the manner of their resolution is never elucidated. Finally, that claim

construction is dependent on underlying factual determinations has been verified by our 

experience, which shows that reviewing these questions de novo has not clarified the 

law, but has instead “distort[ed] the appellate process,” causing confusion among the 

district courts and bar. See Cooter, 496 U.S. at 404 (quoting Pierce, 487 U.S. at 561);

see also Koon v. United States, 518 U.S. 81, 99 (1996). 

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Our purely de novo review of claim interpretation also cannot be reconciled with 

the Supreme Court’s instructions regarding obviousness. While ultimately a question of 

law, obviousness depends on several underlying factual inquiries. Graham v. John

Deere Co., 383 U.S. 1, 17 (1966); see also Dennison Mfg. Co. v. Panduit Corp., 475 

U.S. 809, 811 (1986) (holding that Rule 52(a) requires that the district court’s subsidiary

factual determinations should be reviewed for clear error); cf. Graver Tank & Mfg. Co. v. 

Linde Air Prods. Co., 336 U.S. 271, 275 (1949) (holding that validity, while ultimately a 

question of law, is founded on factual determinations that are entitled to deference). 

“Under [section] 103, the scope and content of the prior art are to be determined; 

differences between the prior art and the claims at issue are to be ascertained; and the 

level of ordinary skill in the pertinent art resolved.” Graham, 383 U.S. at 17. 

To a significant degree, each of these factual inquiries is also necessary to claim

construction. Before beginning claim construction, “the scope and content of the prior 

art [should] be determined,” id., to establish context. The “differences between the prior

art and the claims at issue [should] be ascertained,” id., to better define what the 

inventor holds out as the invention. And, the foundation for both the obviousness and 

claim construction determinations is “the level of ordinary skill in the pertinent art.” Id.; 

see Multiform, 133 F.3d at 1477. These underlying factual considerations receive the 

level of deference due under Rule 52(a) when considering obviousness, but they are 

scrutinized de novo in the claim construction context. As directed by the Supreme 

Court, however, it is especially important in the patent field, “where so much depends

upon familiarity with specific scientific problems and principles not usually contained in 

the general storehouse of knowledge and experience,” to give deference to the district 

03-1269,-1286 7
court’s findings of fact. Graver Tank & Mfg. Co. v. Linde Air Prods. Co., 339 U.S. 605,

609-10 (1950). 

While the court flails about in an attempt to solve the claim construction 

“conundrum,” the solution to our plight is straightforward. We simply must follow the 

example of every other appellate court, which, regarding the vast majority of factual 

questions, reviews the trial court for clear error.6

 This equilibrium did not come about as

the result of chance or permissive appellate personalities, but because two centuries of

experience has shown that the trial court’s factfinding ability is “unchallenged.” Salve

Regina Coll. v. Russell, 499 U.S. 225, 233 (1991); Inwood, 456 U.S. at 856 

(“Determining the weight and credibility of the evidence is the special province of the 

trier of fact.”). Time has similarly revealed that it is more economical for the district 

court to find facts. Pierce, 487 U.S. at 560 (“Moreover, even where the district judge’s 

full knowledge of the factual setting can be acquired by the appellate court, that 

acquisition will often come at unusual expense, requiring the court to undertake the 

unaccustomed task of reviewing the entire record . . . .”). 

Therefore, not only is it more efficient for the trial court to construct the record, 

the trial court is better, that is, more accurate, by way of both position and practice, at

finding facts than appellate judges. Anderson, 470 U.S. at 574 (“The rationale for 

deference to the original finder of fact is not limited to the superiority of the trial judge’s

position to make determinations of credibility. The trial judge’s major role is the 

determination of fact, and with experience on fulfilling that role comes expertise.”);

Zenith Radio Corp. v. Hazeltine Research, Inc., 395 U.S. 100, 123 (1969). Our rejection 

 6 While jurisprudentially sound, the bar also supports this proposition, as 

evident by the many amici curiae briefs urging adherence to Rule 52(a). 

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of this fundamental premise has resulted, not surprisingly, in several serious problems, 

including increased litigation costs, needless consumption of judicial resources, and 

uncertainty, as well as diminished respect for the court and less “decisional accuracy.” 

Salve, 499 U.S. at 233. We should abandon this unsound course.7 

If we persist in deciding the subsidiary factual components of claim construction 

without deference, there is no reason why litigants should be required to parade their 

evidence before the district courts or for district courts to waste time and resources 

evaluating such evidence. It is excessive to require parties, who “have already been 

forced to concentrate their energies and resources on persuading the trial judge that 

their account of the facts is the correct one,” to “persuade three more judges at the 

appellate level.” Anderson, 470 U.S. at 575. If the proceedings before the district court 

are merely a “tryout on the road,” id. (quoting Wainwright v. Sykes, 433 U.S. 72, 90 

(1977)), as they are under our current regimen, it is wasteful to require such

proceedings at all. Instead, all patent cases could be filed in this court; we would

determine whether claim construction is necessary, and, if so, the meaning of the 

claims. Those few cases in which claim construction is not dispositive can be 

remanded to the district court for trial. In this way, we would at least eliminate the time 

and expense of the charade currently played out before the district court. 

Eloquent words can mask much mischief. The court’s opinion today is akin to 

rearranging the deck chairs on the Titanic—the orchestra is playing as if nothing is

amiss, but the ship is still heading for Davey Jones’ locker.

 7 There are some scenarios where it is difficult to weed facts from law, see

Pullman-Standard, 456 U.S. at 288, but claim construction is not one of them. 

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