Source: s3://data.kl3m.ai/documents/govinfo/USCOURTS/USCOURTS-caed-1_05-cv-01411/USCOURTS-caed-1_05-cv-01411-8/pdf.json

Nature of Suit Code: 830
Nature of Suit: Patent
Cause of Action: 35:271 Patent Infringement

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UNITED STATES DISTRICT COURT

EASTERN DISTRICT OF CALIFORNIA

DUHN OIL TOOL, INC.

Plaintiff,

v.

COOPER CAMERON CORPORATION,

Defendants.

1:05-CV-01411 OWW LJO

MEMORANDUM DECISION AND ORDER

RE CLAIM INTERPRETATION 

1. INTRODUCTION

Before the court are the parties’ motions for a Markman

claim interpretation of United States Patent No. 6,920,925 (the

“‘925 Patent” or the “Patent”). (Doc. 40, Duhn Oil’s Claim

Construction Brief, Filed August 21, 2006 (“Pl. Brief”); Doc.

43, Defendant’s Opening Markman Brief, Filed August, 21, 2006

(“Def. Brief”).) Oral argument was heard on October 11, 2006. 

2. PROCEDURAL HISTORY

Plaintiff Duhn Oil Tool, Inc. (“Duhn Oil” or “Plaintiff”)

filed its complaint for patent infringement against Defendant

Cooper Cameron Corporation (“Cameron” or “Defendant”) on November

11, 2005. (Doc. 1, Complaint.) Cameron answered and filed a

counterclaim for declaratory relief of patent invalidity against

Duhn Oil on May 17, 2006. (Doc. 15, Def.’s Answer and

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Counterclaim.) On April 12, 2006 Duhn Oil filed and answer to

Cameron’s counterclaim. (Doc. 18, Pl.’s Answer to Counterclaim.) 

Cameron filed a motion for summary judgment on July 15,

2006. (Doc. 26, Motion for Summary Judgment.) On August 4, 2006

Duhn Oil opposed the motion. (Doc. 31, Opposition.) On August

14, 2006, Cameron filed a reply to the opposition. (Doc. 33,

Reply/Response to Opposition.) 

On August 21, 2006 Duhn Oil filed a claim construction brief

for a Markman hearing. (Doc. 43, Duhn Oil’s Claim Construction

Brief.) On September 5, 2006 Cameron filed its opposition to the

brief. (Doc. 47, Cameron’s Markman Opposition Brief.) 

Cameron filed its claim construction brief on August 21,

2006. (Doc. 43, Cameron’s Motion for Claim Construction.) On

September 5, 2006 Duhn Oil filed its opposition. (Doc. 44, Duhn

Oil’s Markman Opposition Brief.)

3. FACTUAL BACKGROUND

A. Origin of Litigation 

Duhn Oil designs and manufactures quality completion

products for the oil industry. (Doc. 1, Complaint, ¶ 4.) Duhn

Oil’s products are sold throughout the United States. (Id.) On

February 19, 2003 Duhn Oil filed an application with the United

States Patent and Trademark Office (“USPTO”) to obtain a patent

for a wellhead isolation tool and a wellhead assembly

incorporating such a tool. (Id., ¶ 5.) The application matured

into the ‘925 Patent entitled “Wellhead Isolation Tool” and the

patent was issued on July 26, 2005. 

Duhn Oil sues Cameron for patent infringement alleging that

Defendant has offered products for sale in the United States that

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infringe on Duhn Oil’s ‘925 patent. (Id., ¶ 6.) Duhn Oil

accuses Defendant of violating its ‘925 patent under 35 U.S.C. §

271. (Id., ¶ 7.) Duhn Oil argues that it has been damaged by

the infringement and seeks the following relief: 

1. Declaratory judgment that the ‘925 patent is valid and

is owned by Plaintiff.

2. Declaratory judgment that Defendant has committed acts

of patent infringement by its offer for sale and sale of

products that infringe the ‘925 patent. 

3. Defendant should be enjoined from infringing on the

patent. 

4. A mandatory injunction for Cameron to deliver to Duhn

Oil for destruction any and all products in Defendant’s

possession embodying the patented invention as well as

any promotional literature therefore. 

5. Damages.

6. Prejudgment interest on infringement damages. 

7. Costs.

8. Any other relief that the court may deem just and

proper. 

(Doc. 1, Complaint.) 

Defendant Cameron denies infringing Duhn Oil’s ‘925 patent

and filed counterclaims asserting:

1. Duhn Oil has failed to state a claim upon which relief

can be granted. 

2. Defendant is not infringing and has never infringed,

either directly or indirectly any valid claim of the

‘925 patent. 

3. The claims of the ‘925 patent are invalid for failure to

meet the conditions of patentability in 35 U.S.C. §§ 102

and 103, and for failure to comply with requirements of

35 U.S.C. § 112. 

4. Duhn Oil failed to disclose material information with

the intent to deceive the USPTO in applying for the ‘925

patent. The patent is unenforceable due to the actions

and or omissions of Plaintiff and its agents

constituting inequitable conduct during the prosecution

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 35 U.S.C. § 287 provides that in the event of such a 1

failure to mark “no damages shall be recovered by the patentee in

any action for infringement, except on proof that the infringer

was notified of the infringement [which includes the filing of an

action for infringement] and continued to infringe thereafter, in

which event damages may be recovered only for infringement

occurring after such notice.” 

 This description is taken entirely from Doc. 43, 2

Defendant’s Opening Markman Brief, Filed August 21, 2006.

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of the application that issued as the ‘925 patent. 

5. Plaintiff is estopped from enforcing the ‘925 patent as

alleged because of statements, representations and

admissions made, and/or actions taken during the

prosecution of a related continuation application. 

6. Plaintiff’s claims are barred, in whole or in part, by

the doctrine of equitable estoppel. 

7. Plaintiff is precluded from recovering any alleged

damages for any patent infringement occurring prior to

the filing date of its complaint. Plaintiff has failed

to plead, and cannot prove, compliance with the marking

requirements of 35 U.S.C. § 287.1

(Doc. 15, Def.’s Answer and Counterclaims To Plaintiff’s

Complaint.) 

B. Background of the ‘925 Patent2

Duhn Oil is the owner of the ‘925 patent. The ‘925 Patent,

entitled “Wellhead Isolation Tool,” generally relates to a

wellhead assembly used in high-pressure fracturing operations. 

Fracturing operations are used to stimulate an existing well’s

hydrocarbon production and involve introducing generally abrasive

material into the well’s producing regions at very high pressure. 

The wellhead assembly described in the ‘925 Patent includes a

casing head coupled to the wellbore, and a tubing head mounted

over the casing head. The tubing head has a first radial flange

extending from it at an upper end. The wellhead isolation tool,

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 The adjective use of the term “elongate” is defined as 3

“stretched out.” Merriam-Webster’s Collegiate Dictionary,

Eleventh Edition, http://www.m-w.com,(last visited January 22,

2007.) 

 The term “annular” is defined as “of, relating to, or 4

forming a ring.” Merriam-Webster’s Collegiate Dictionary,

Eleventh Edition, http://www.m-w.com,(last visited January 22,

2007.) 

 The term “member” is defined as “a part of a whole.” 5

Merriam-Webster’s Collegiate Dictionary, Eleventh Edition,

http://www.m-w.com,(last visited January 22, 2007.) 

 Defendant states that claims 1 and 37 recite similar 6

limitations and are sufficiently represented by the broader

language of claim 1. (Doc. 43, Def.’s Markman Brief.) Even

though claims 1 and 37 are the only independent claims at issue,

Duhn Oil argues that the following claims are dependent on claim

1, either directly or indirectly, and are therefore also at issue

as being infringed by Defendant in this case: Claims 2-6, 10-12,

19, 28-30, and 34-36. (Doc. 40, Pl. Markman Brief.) Defendant

only disputes claims 1 and 37 and, for this reason, only claims 1

and 37 are addressed in this order.

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or “frac mandrel,” is suspended concentrically (circularly) 

within the tubing head and aligned with a production casing

suspended below in the wellbore. The frac mandrel is a generally

elongate annular member , and has a second radial flange 3 4 5

extending from it. In some embodiments, the first flange

extending from the tubing head and the second flange extending

from the frac mandrel are fastened together. When assembled with

respect to the wellhead assembly, the frac mandrel isolates to

protect certain wellhead components from the extreme pressures

used during well stimulation processes such as fracturing. 

C. Claims At Issue6

Claim 1 specifies a wellhead assembly having various

components as follows: 

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1. A wellhead assembly comprising: 

• a casing;

• a first tubular member mounted over the casing;

• a first tubular member flange extending from the first

tubular member;

• a generally elongate annular member (“frac mandrel”)

suspended in the first tubular member, said annular member

having a first end portion extending above the first tubular

member and a second end portion below the first end portion;

• a secondary flange extending from the frac mandrel;

• a plurality of fasteners fastening the secondary flange to

the first tubular member flange; and

• a production tubular member aligned with the frac mandrel,

wherein an axial force acts on the generally frac mandrel

and is reacted in both the first tubular member flange and

the secondary flange.

(Doc. 41, Ex. 1, Filed August 21, 2006.) 

Claim 1 identifies the components either by their location

and/or their functionality. For example, the production tubular

member is aligned with the annular member in such a way that an

axial force acts on the annular member and such force is reacted

in the first tubular member flange and the secondary flange to

which it is attached. 

i. Terms in Dispute

The parties dispute two terms found in Claims 1 and 37. The

first set of disputed terms relate to the “extending from

language” in the claims: 

C Claim 1: “...a secondary flange extending from the elongate

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 The disputed term “extend” is used throughout the patent. 7

Though the term is given different locational references it is

used in the same way as describing a starting point for the

location of one component as stretching out towards the path or

direction of another component. 

7

annular member...” 

C Claim 37: “...a second flange extending from the generally

elongate annular member...” and the variant, “said annular

member having a first end portion extending above the first

tubular member...”7

Duhn Oil argues for a broad reading of the term “extending

from” interpreted as “located or stretching outwardly.” This

interpretation would include products that abut each other. 

Cameron argues that the term “extending from” should be narrowly

construed and limited to only include products that have a

structural relationship and are either integral or mechanically

connected to each other. This interpretation would not include

products that abut each other. 

The second set of disputed terms relate to the “wherein

clause” of claims 1 and 37: 

C Claim 1: “...wherein an axial force acts on the generally

elongate annular member and is reacted in both the first

tubular member flange and the secondary flange...” 

C Claim 37: “...wherein an axial force acts on the generally

elongate annular member and is reacted in both the first

tubular member flange and the secondary flange...” 

Duhn Oil argues that the absence of the word “means” in the

“wherein” clause gives rise to a presumption that it is not a

“means-plus-function” claim. Duhn Oil maintains that the

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“wherein clause” should not be construed as a “means-plusfunction” claim because the “wherein clause” explicitly

identifies both a function and the structures which perform the

claimed function. 

Cameron, on the other hand, argues that the “wherein clause”

should be construed as a “means-plus-function” claim because the

clause uses functional language but does not recite any structure

for performing the claimed function.

4. STANDARD OF REVIEW

Liquid Dynamics Corp. v. Vaughn Co., 355 F.3d 1361 (Fed.

Cir. 2004) explains:

An infringement analysis entails two steps. The first step

is determining the meaning and scope of the patent claims

asserted to be infringed. The second step is comparing the

properly construed claims to the device accused of

infringing.” Cybor Corp v. FAS Techs., Inc, 138 F.3d 1448,

1454 (Fed. Cir. 1998). The first step, claim construction,

is a question of law. Id. at 1451. The second step is

factual. Bai v. L & L Wings, Inc., 160 F.3d 1350, 1353

(Fed. Cir. 1998). When construing a claim, a court

principally consults the evidence intrinsic to the patent,

viz., the claims themselves, the written description portion

of the specification, and the prosecution history. See

Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582-83

(Fed. Cir. 1996).

Liquid Dynamics Corp., 355 F.3d at 1367.

A patent is a fully integrated document. It must set out a

written description of the invention “in such full, clear,

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concise, and exact terms as to enable any person skilled in the

art to which it pertains” to practice the invention. 35 U.S.C. §

112. The written description required by 35 U.S.C. § 112 must

clearly allow persons of ordinary skill in the art to recognize

that the inventor invented what is claimed. Reiffin v. Microsoft

Corp., 214 F.3d 1342, 1346 (Fed. Cir. 2000). Adequate

description of the invention guards against the inventor’s

overreaching by insisting that he recount his invention in such

detail that his future claims can be determined to be encompassed

within his original creation. Id. In interpreting the meaning

of an asserted claim, a court should first refer to the following

sources of intrinsic evidence: the patent claims, the

specification, and the prosecution history. See Interactive Gift

Express, Inc. v. Compuserve Inc., 256 F.3d 1323, 1331 (Fed. Cir.

2001); See also, Phillips Petroleum Co. v. Huntsman Polymers

Corp., 157 F.3d 866, 870 (Fed. Cir. 1998); Vitronics Corp., v.

Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996). 

Intrinsic evidence alone will usually be sufficient to resolve

any ambiguities in disputed claim terms. See Vitronics, 90 F.3d

at 1583. In such cases, extrinsic evidence should not be

considered. See id.

A. Patent Language

Patent claims are the numbered paragraphs at the end of a

patent’s specification that define the scope of the patent. 

Trinity Indus. v. Road Sys., 121 F. Supp. 2d 1028, 1033 (Fed.

Cir. 2000.) The threshold issue in any patent infringement case

is claim construction because it is necessary to understand the

scope of the patent’s claims to determine whether the accused

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device infringes the patent. Id. Claim construction is a

question of law for the court to decide. Id. In construing the

meaning of disputed claim terms, the court first looks to the

words (both asserted and nonasserted) of the claims themselves. 

See Vitronics, 90 F.3d at 1582. “[T]he language of the claim

defines the scope of the protected invention.” Bell Comm.

Research, Inc. v. Vitalink Comm., Corp., 55 F.3d 615, 619 (Fed.

Cir. 1995); see also Vitronics, 90 F.3d at 1582. Words are

generally given their ordinary and plain meaning, although a

patentee may choose to be a lexicographer and define a word in a

way other than its ordinary meaning. See id. (citing Hoechst

Celanese Corp. v. BP Chems. Ltd., 78 F.3d 1575, 1578 (Fed. Cir.

1996) (“A technical term used in a patent document is interpreted

as having the meaning that it would be given by persons

experienced in the field of the invention, unless it is apparent

from the patent and the prosecution history that the inventor

used the term with a different meaning.”). The words of the

claim are interpreted in accordance with their ordinary meaning,

as understood by a person reasonably skilled in the art. See

Quantum Corp. v. Rodime, PLC, 65 F.3d 1577, 1580 (Fed. Cir.

1995); Vitronics, 90 F.3d at 1582; Intellicall, Inc. v.

Phonometrics, Inc., 952 F.2d 1384, 1387 (Fed. Cir. 1992). 

Technical terms should be construed from the perspective of a

person experienced in the field of the invention. See CVI/Beta

Ventures, Inc. v. Tura LP, 112 F.3d 1146, 1153 (Fed. Cir. 1997). 

A USPTO examiner is a person skilled in the art of the patent. 

See, In re Lee, 277 F.3d 1338, 1345 (Fed. Cir. 2002)(the

foundation of the principle of judicial deference to the rulings

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of agency tribunals is that the tribunal has specialized

knowledge and expertise such that when reasoned findings are

made, a reviewing court may confidently defer to the agency’s

application of its knowledge in its area of expertise.) In order

to ascribe a special definition to a claim term, the definition

must be clearly stated in the patent specification or the file

history. Vitronics, 90 F.3d at 1582 (citations omitted). A

claim should not be construed in a manner that renders the claim

language meaningless or superfluous. Texas Instruments, Inc. v.

United States Int’l Trade Comm’n, 988 F.2d 1165, 1171 (Fed. Cir.

1993).

B. Specification 

The claims “must be read in view of the specification, of

which they are a part.” Markman, 52 F.3d at 979. Section 112

provides:

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, or with which it is most nearly connected, to make

and use the same, and shall set forth the best mode

contemplated by the inventor of carrying out his invention.

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.

35 U.S.C. § 112, ¶¶ 1-2.

The specification is reviewed “to determine whether the

inventor has used any terms in a manner inconsistent with their

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ordinary meaning.” Vitronics, 90 F.3d at 1582; CVI/Beta

Ventures, 112 F.3d at 1153. If the inventor uses a term in a

manner other than its ordinary meaning, that meaning is given

effect because the inventor is free to be his or her own

lexicographer. See Vitronics, 90 F.3d at 1582 (citing Hoechst,

78 F.3d at 1578). In this regard, the specification “may act as

a sort of dictionary.” Markman, 52 F.3d at 979. The

specification can define terms either explicitly or by

implication. See Vitronics, 90 F.3d at 1582 (citing Markman, 52

F.3d at 979).

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.” Vitronics,

90 F.3d at 1582. Though claims should always be read in view of

the specification, the Federal Circuit cautions that the scope of

a claim should not be limited to specific embodiments disclosed

in the specification. See, e.g., Ekchian v. Home Depot, Inc.,

104 F.3d 1299, 1303 (Fed. Cir. 1997); Intervet America, Inc. v.

Kee-Vet Labs., Inc., 887 F.2d 1050, 1053 (Fed. Cir. 1989).

C. Prosecution History

When construing the language of a claim, the prosecution

history of the patent should be considered, provided that it is

in evidence. Southwall Tech., Inc. v. Cardinal IG Co., 54 F.3d

1570, 1576 (Fed. Cir. 1995); Markman, 52 F.3d at 980; Vitronics,

90 F.3d at 1582 (citing Graham v. John Deere, 383 U.S. 1 (1966));

CVI/Beta Ventures, 112 F.3d at 1155. The prosecution history, or

file wrapper, of the patent provides a complete record of all

proceedings, including all express representations made by the

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patent applicant regarding the scope of the claims, before the

USPTO. See Vitronics, 90 F.3d at 1583. The file wrapper limits

the scope of a claim term so as to exclude any interpretation

disclaimed during prosecution of the patent. See id. at 1583

(citing Southwall Tech., 54 F.3d at 1576); CVI/Beta Ventures, 112

F.3d at 1155. In addition, any prior art cited during the

prosecution history may indicate what the patent claims do not

cover. See Vitronics, 90 F.3d at 1583 (citing Autogiro Co. of

America v. United States, 181 Ct. Cl. 55, 384 F.2d 391, 399 (Ct.

Cl. 1967)). However, the prosecution history “cannot enlarge,

diminish, or ‘vary’ the limitations in the claims.” Markman, 52

F.3d at 980 (quoting Goodyear Dental Vulcanite Co. v. Davis, 102

U.S. 222, 227 (1880)). 

D. Extrinsic Evidence 

Extrinsic evidence may be resorted to only for

interpretation of terms used in the claim and specification when

their meaning is in dispute or ambiguous. See Vitronics, 90 F.3d

at 1584-85. Extrinsic evidence is “all evidence external to the

patent, including expert and inventor testimony, dictionaries,

and learned treatises.” Markman, 52 F.3d at 979, 980. Extrinsic

evidence may be consulted during construction of a claim to

assist with the understanding of “scientific principles, the

meaning of technical terms, and terms of art that appear in the

patent and prosecution history.” Markman, 52 F.3d at 980; see

Vitronics, 90 F.3d at 1584. Extrinsic evidence may be received

to aid in “‘coming to a correct conclusion’ as to the true

meaning of the language employed in the patent.” Markman, 52

F.3d at 979 (citations omitted). After consideration of all

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available intrinsic evidence, if there still is some genuine

ambiguity in the claims, extrinsic evidence may be consulted to

interpret the meaning of the language used in the claim. See

Vitronics, 90 F.3d at 1584. Extrinsic evidence cannot be used,

however, for the purpose of varying or contradicting the terms of

the claims. See id.

5. DISCUSSION

A. SHOULD THE TERM “EXTENDING FROM” IN CLAIMS 1 AND 37 BE

LIMITED TO PRODUCTS THAT ARE MECHANICALLY CONNECTED OR

SHOULD IT BE CONSTRUED TO ALSO INCLUDE PRODUCTS THAT ABUT

EACH OTHER BUT HAVE NO MECHANICAL CONNECTION?

i. Patent Language Arguments

An analysis of the ‘925 patent language indicates that the

term “extending from” is not limited to “integral or mechanically

connected” structural relationships. Interpreting “extending

from” as limiting the structural relationship between the

secondary flange and the frac mandrel to being either an integral

or mechanical connection, improperly confines the term “extending

from” to specific embodiments of the invention. Phillips v. AWH

Corp., 415 F.3d 1303, 1323 (Fed. Cir. 2005)(although the

specification describes very specific embodiments of the

invention, we have repeatedly warned against confining the claims

to those embodiments.)

Cameron disagrees. Cameron first argues that the “extending

from” language is not specifically defined in the ‘925 patent. 

Cameron asserts that a structural relationship characterized as

an abutment, as opposed to being integral or mechanically

connected, is not contemplated by the purported invention

disclosed and claimed in the ‘925 patent. Cameron, however,

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fails to explain why the patent’s failure to contemplate the

structural relationship of an abutment limits the “extending

from” clause to being integral or mechanically connected. In

essence, Cameron requests that the court interpret the patent’s

“extending from” language to give it the meaning, “integral or

mechanically connected,” which goes beyond the patent’s express

language to add a meaning that is neither obvious nor required. 

The structural relationship of an abutment contemplates a

relationship where two structures that abut (are in contact or

adjacent to each other) “extend from” each other. 

Cameron next argues that Duhn Oil’s interpretation of

“extending from” is inconsistent with the “wherein” clause and

would render the claimed device inoperable. According to

Cameron, Duhn Oil’s interpretation only requires that the

secondary flange be positioned “outward” of the frac mandrel with

no requirement that the flange be connected to the frac mandrel,

or even be touching the frac mandrel in any way. Cameron argues

that this proposed definition is overbroad. According to

Cameron, under Duhn Oil’s construction there would be no way for

the force to transmit from the frac mandrel to its secondary

flange because it does not require that the secondary flange even

touch the frac mandrel. It only requires that it be “positioned

outward.” 

However, the "wherein" clause does not require that the

"secondary flange" be mechanically connected to, or integral

with, the frac mandrel as Cameron contends. The axial force

could be reacted to independently by the "first tubular member

flange" and the "secondary flange" if they are in contact without

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 Claim 12 reads: “A wellhead assembly as recited in claim 4 8

wherein the secondary flange is separate from the elongate

annular member (frac mandrel).” 

 Claim 4 reads: “A wellhead assembly as recited in claim 1 9

further comprising a seal between the elongate annular member

second end portion and the first tubular member.” 

16

being integrally connected. Claim 12 states the wellhead 8

assembly of claim 4 which incorporates by reference the wellhead 9

assembly of claim 1 "wherein the secondary flange is separate

from the elongate annular member (frac mandrel)." Since a

dependent claim is narrower in scope than the independent claim

on which it depends, claim 1 includes embodiments of the wellhead

assembly wherein the secondary flange is either separate from or

connected to the frac mandrel. Similarly, claim 46 claims the

wellhead assembly of claim 37 "wherein the first tubular member

and the secondary flange are fastened together," thereby

demonstrating that claim 37 also claims embodiments of the

wellhead assembly wherein the secondary flange is either separate

from or connected to the frac mandrel. The construction of the

term "extending from" taken in conjunction with the "wherein"

clause of claims 1 and 37 is consistent with the scope of those

claims and does not render either of those claims inoperative.

ii. Specification Arguments

When construing the “extending from” term in light of the

specification, Figure 4b of the patent shows that the term is

broader than Cameron asserts. For example, Fig. 4b depicts an

embodiment of the claimed invention where the “lock screws 40...

are threadedly retracted to allow unrestricted access through

bore 92 defined through the secondary flange.” Because the lock

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screws 40 are retracted in this embodiment, they do not interact

with the annular groves 212, 214 of the frac mandrel 60, and

therefore cannot be said to be “mechanically connected” to the

elongate annular member 60 (frac mandrel). Fig. 4b, thus,

explicitly discloses an embodiment of the present invention where

the “secondary flange” is not integral with or mechanically

connected to the frac mandrel 60.”

Cameron argues that Duhn Oil’s construction is inconsistent with

the disclosure set forth in the ‘925 patent specification. 

According to Cameron the ‘925 patent specifications reveal that

the use of the term is limited to reference to “integral” parts

of a single structural component of the wellhead assembly

described in the patent. For example, the ‘925 Patent describes

an integral flange that connects to a fracturing tree as “[a]

radial flange 208 [that] extends from an upper end of the

wellhead isolation tool.” Moreover, the non-integral secondary

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flanges 70 and 110 illustrated in the ‘925 Patent are never

described as “extending from” the mandrel. Only in the claims of

the ‘925 Patent is the secondary flange first described as

“extending from” the mandrel. Thus, although ‘925 Patent

describes non-integral alternatives for the secondary flange,

interpreting the recitation “extending from” in a manner

consistent with the written description suggests that this

recitation is limited to an integral or one-piece relationship. 

Cameron also argues that term “extending from is never defined

and there is no explanation of the term found in the prosecution

history.” 

According to Cameron the relationship between the frac

mandrel and the secondary flange is described in three different

ways in the patent specifications: 

1. Mechanically connected: Duhn Oil emphasizes that

the secondary flange is disclosed as a separate

part slid over the frac mandrel and positioned

outwardly of the frac mandrel but fails to address

the fact that the secondary flange is mechanically

connected.

2. Integral: the secondary flange is described as

being an “integral” part of the frac mandrel at

Col. 3, lines 25-27, and at Col. 7, lines 22-24. 

3. Threaded Connection: the “secondary tie down

flange” described as secured to the frac mandrel

with a threaded connection. (Col. 3, lines 28-37,

and Col. 7, lines 17-22.)

Cameron argues that there are no other possible

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configurations contemplated or disclosed in the ‘925 Patent.

There is no suggestion in the ‘925 Patent that the secondary

flange is or may be disposed around but not connected to the

mandrel. Cameron argues that the entire context of the ‘925

Patent evidences that the secondary flange is, at a minimum,

mechanically connected to the mandrel. Lastly, Cameron argues

that every described embodiment of the invention requires some

sort of mechanical connection between the secondary flange and

the mandrel and that the mechanically extending flanges are not

just examples of flanges but are the only extending flanges

contemplated and claimed in the ‘925 patent. According to

Cameron, the only logical conclusion is to construe “extending

from” as either integral or having a mechanical connection. 

Because Cameron’s products merely abut each other, Cameron argues

that they do not infringe. 

Cameron correctly argues that the “extending from” language

is not specifically defined in the ‘925 patent. However, it does

not follow that an abutment relationship is not included merely

because the term “extending from” is not defined. To determine

the meaning of the term “extending from” an analysis of the

term’s use in the patent language and a comparison to the

specifications is required. 

Claim 1 describes a first tubular member flange “extending

from” the first tubular member. In a separate provision, Claim 1

also describes “a plurality of fasteners fastening the secondary

flange to the first tubular member flange.” If the term

“extending from” were to only contemplate a mechanical

connection, then the term describing the relationship between the

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secondary flange and the first tubular member through a plurality

of fasteners would not be necessary. 

Claim 3 describes “a wellhead assembly as recited in claim 2

wherein said annular lip extends radially inward defining an

opening having a first diameter, wherein the elongate annular

member first end portion comprises an inner surface having a

second diameter and wherein the portion of the production tubular

member comprises an inner surface having a third diameter,

wherein said first, second and third diameters are equal.” An

embodiment of this claim is found in Fig. 3. A close analysis of

Fig. 3 shows the annular lip “extending” into the inner bore. 

There is no mechanical connection contemplated in this diagram or

description. Both the diagram and the description show an

abutment but not a connection 

Claim 37 describes, “A wellhead assembly comprising... a

generally elongate annular member (frac mandrel) suspended in the

first tubular member and said annular member having a first end

portion extending above the first tubular member and a second end

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portion below the first end portion within the first tubular

member , wherein the elongate annular member comprises an outer 10

surface before the first and second ends, wherein a portion of a

section of the outer surface of the elongate annular member mates

with the smaller diameter inner surface section of the first

tubular member.” 

An analysis of this claim and a comparison of Fig. 1

indicates that the lower portion of the frac mandrel is encased

by the upper portion of the first tubular member flange. A

visual assessment of Fig. 1 reveals that the upper portion of the

frac mandrel abuts from the first tubular member. Further, the

fact that the frac mandrel is “suspended” in the first tubular

member indicates a relationship where the first tubular member is

holding the frac mandrel in place by encasing it rather than

through a threaded or mechanical connection. There is no

description of any mechanical connection in either the language

of this claim or in the visual description of the embodiment in

Fig. 1. 

Claim 50 describes “A wellhead assembly as recited in claim

37 further comprising a third flange extending from the generally

elongate annular member spaced apart from the second flange.” In

Fig. 1 the third flange is indicated by no. 208 on the diagram. 

There is no mechanical or threaded connection contemplated in the

relationship between the third flange and the frac mandrel. The

third flange abuts the frac mandrel. 

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Claim 59 describes “A wellhead assembly as recited in claim

52 wherein a portion of the first tubular member extends within a

casing head coupled to the casing, the wellhead assembly further

comprising... an annular hanger suspended in the casing head...

wherein the first tubular member comprises a lower section within

the upper inner surface section of the annular hanger and wherein

the second end portion of the elongate annular member extends to

the intermediate inner surface section of the annular hanger

sandwiching a portion of the first tubular member lower section

between the outer surface of the elongate annular member and the

upper inner surface of the annular hanger...” 

Similarly, the language of claim 50 compared to Fig. 1 does

not indicate a threaded or mechanical connection between the frac

mandrel, the casing head, and the first tubular member. 

According to Fig. 1, all three components meet at the area of the

inner surface section of the annular hanger. The components abut

each other in Fig. 1 and have a relationship where some

components are “suspended” by others in the relationship. 

Neither the language nor the diagram indicates any mechanical

connection. 

Based on a comparison between the language of the claims and

the attached diagrams of the patent, it cannot be said that the

term “extending from” was meant to only be limited to components

that are mechanically connected. 

iii. Prosecution History

The Patent Examiner who is skilled in the art, interpreted

the term “extending from” to cover a wide variety of different

structural relationships between the flange and the member it

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“extends from.” The common feature of all these configurations

is that the flange is “located or stretching outwardly from the

frac mandrel.” During the prosecution the Examiner used the term

“extending from” to cover various flange structures including a

use where the structure was “integral,” but he did not limit the

application of “extending from” to that structure. Duhn Oil

cites the Examiner’s references to prior art in the prosecution

history of the ‘925 patent. 

For example in the Smith ‘194 patent The Examiner describes

flange 20 threaded on member 19 as “extending from” that member. 

He also describes Flange 22 slipped over member 34 as “extending

from” that member. (Doc. 40, Ex. 2, Part 6., P. 247, Office

Action dated 10/05/2004). 

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In the Cornelssen et al ‘386 Patent, Flange 120, which rests

on top of member 10 but has a wider diameter than member 10, is

described by the Examiner as “extending from” that member. (Id.)

In the Van Bilderbeek ‘596 patent: The Examiner describes

flange 330 as “extending from” the member of which it is an

integral part. (Doc. 40, Ex. 2, Part 8, P. 316, Office Action

dated 1/18/2005). 

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Based on the prosecution history of the patent, regardless

of in what configuration the term “extending from” is used, all

of the uses comprise a structure which is projecting from or

abuts another structure. This is consistent with the ordinary

meaning of “extending from” which describes the relative position

of two components or portions of a component, not how they are

connected. 

Cameron disputes Duhn Oil’s use of the prosecution history

arguing that Duhn Oil’s proposed construction is inconsistent

with the arguments it made before the USPTO during the

prosecution of the application that issued the ‘925 Patent and it

should be estopped to deny the position it then took. Cameron

first argues that Duhn Oil is precluded from asserting the

“extending from” language of the Smith ‘194 patent and the

Cornelssen ‘386 patent because the USPTO’s references to the

Smith ‘194 patent and the Cornelssen ‘386 patent were made in

rejecting Duhn Oil’s then pending patent claims. Cameron argues

that the Examiner rejected a number of Duhn Oil’s claims

including claims 1 and 37 in the office action of October 5,

2004. Defendant asserts that Duhn Oil then “refused to agree

that the flanges and frac mandrels identified by the Examiner

disclosed the claimed ‘secondary flange’ and frac mandrel of the

issued claims 1 and 37 in the ‘925 patent.” According to

Cameron, Duhn Oil effectively asserted that the “secondary

flange” identified by the Examiner was not “extending from” the

frac mandrel disclosed in the Smith and Cornelssen prior art

patents because Duhn Oil referred to those flanges and frac

mandrels as the “alleged” secondary flange and the “alleged” frac

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 In support of its argument, Cameron cites Cybor Corp. v

11

FAS Technologies, Inc., 138 F.3d 1448, 1457 (Fed. Cir. 1998.) for

the rule that when a patentee takes a position before the USPTO

during prosecution of a patent application, the patentee should

be barred from asserting an inconsistent position on claim

construction. However, Duhn Oil did not take an inconsistent

position during the prosecution of the case. 

Phillips also provides a warning on the use of 12

dictionaries and other external sources. The court states: “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. Phillips, 415 F.3d at 1324. This problem

does not exist in this case where the focus is instead on how

Duhn Oil used the claim term in the claims, specification, and

prosecution history, rather than starting with a broad definition

and limiting it by the claims and specifications language.

26

mandrel. This argument does not follow. Referring to the 11

secondary flange and the frac mandrel as “alleged” in the Smith

and Cornelssen patents is not the logical equivalent asserting

that those two components do not extend from each other. 

However, the secondary flange, which was added along with

the “extending from” phrase and is one of the components that

participates in the reaction to fracturing force, was the element

added to overcome the rejection based on the Smith ‘194 patent. 

Duhn Oil argues that the presence of the secondary flange, and

not its particular location, was the point of distinction. The

amendment does not limit Duhn Oil’s ability to claim the

definition of “extending from” to include the relative location

disclosed in the ‘194 patent.

iv. Extrinsic Evidence 

In support of its argument, Duhn Oil refers to the

dictionary meaning of the terms. The ordinary meaning of the 12

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terms “extend” and “from” are readily apparent, and it is proper

to use a dictionary definition to ascertain their meaning. 

Phillips 415 F.3d at 1314 (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... In such

circumstances, general purpose dictionaries may be helpful.)

The term “extending” is commonly defined as “to jut out:

stick out: protrude, project.” (Doc. 45. Schwartz Decl., Ex. 3,

Filed September 5, 2006.) Further the term “from” is commonly

defined as “used as a function word to indicate a starting

point.” (Id.) Thus, the phrase “extending from” means to

“protrude” from a “starting point.” However, the definitions of

“extending” or “from,” separately or in combination do not

require that whatever is “protruding” from the “starting point”

be “integral or “mechanically connected” to the “starting point.” 

The ‘925 patent only requires that one structure be positioned so

as to stretch or protrude outwardly in relation to the other

structure. 

B. IS THE LANGUAGE OF THE “WHEREIN” CLAUSE IN CLAIMS 1 AND 37

PURELY FUNCTIONAL SO AS TO BE INTERPRETED AS A “MEANS-PLUSFUNCTION” CLAIM UNDER 35 U.S.C. § 112, ¶ 6 OR DOES THE

LANGUAGE DESCRIBE BOTH A FUNCTION AND A STRUCTURE SO THAT

INTERPRETING THE CLAUSE AS A “MEANS-PLUS-FUNCTION” CLAIM

WOULD BE IMPROPER? 

The disputed language of the “wherein” clause states: “A

wellhead assembly comprising... a production tubular member

aligned with the elongate member, wherein an axial force acts on

the generally elongate member and is reacted in both the first

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tubular member flange and the second flange.” 

The primary tools used by courts to discern the meaning of

claim terms are the specifications and the prosecution file

history. see, Phillips v. AWH Corp., 415 F.3d. 1303, 1313 (Fed.

Cir. 2005). The intrinsic evidence is the first and principal

step toward determining the meaning of the claims. see also,

Vitronics Corp., 90 F3d at 1582. While the court should look to

the specification for guidance as to how to interpret the

ordinary meaning of a claim term, it must avoid importing

limitations into the claims from the specification. See

Phillips, 415 F.3d at 1323. 

A patent is presumed to be valid. 35 U.S.C. § 282. “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.” 

Phillips, 415 F.3d at 1327. In such cases, we have looked to

whether it is reasonable to infer that the USPTO 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. Id. The applicability of the

doctrine in a particular case therefore depends on the strength

of the inference that the USPTO would have recognized that one

claim interpretation would render the claim invalid, and that the

USPTO would not have issued the patent assuming that to be the

proper construction of the term. Id. at 1328. A defendant

challenging the patent by arguing that the patent itself proves

its own invalidity, must demonstrate such proof clearly and

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convincingly. see, e.g. University of Rochester v. G.D. Searle &

Co., Inc., 358 F.3d 916, 930 (Fed. Cir. 2004.) However, when

claims are amenable to more than one construction, they should,

when reasonably possible, be interpreted so as to preserve their

validity. Modine Mfg. Co. v. U.S. Int’l Trade Comm’n, 75 F.3d

1545, 1557 (Fed. Cir. 1996.) 

I. The language of the “wherein” clause of claims 1

and 37 represents a functional limitation and not

a method step.

Courts have interpreted functional language in an apparatus

claim as requiring that an accused apparatus possess the

capability of performing the recited function. See Intel Corp.

v. U.S. Int’l Trade Comm’n, 946 F.2d 821, 832 (Fed. Cir. 1991.) 

Functional language is nothing more than defining something by

what it does rather than by what it is. In re Swinehart, 55

C.C.P.A. at 1030. In contrast to “functional language” a

“method” limitation recites a process or a step for using an

apparatus. 

In the present case, the language of the “wherein” clause of

claims 1 and 37 does nothing more than define how the “first

tubular member flange” and the secondary flange react when an

axial force acts on the frac mandrel. Accordingly the “wherein”

clause assumes the presence of an axial force. The clause does

not require that an axial force be applied by a user nor does it

specify a method as to how the force is provided. The clause

only requires that a wellhead assembly be subject to an axial

force. Contrary to Cameron’s contention, the axial force of the

wherein clause can be any axial force and is not limited to the

excess loads caused during fracturing. The axial force can

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include forces due to gravity, pressure from the well, or any

other environmental force that could act on the wellhead

assemblies of claims 1 and 37. 

Further, the language of claims 1 and 37 does not require

that the device be in use to infringe. One can infringe claims 1

and 37 simply by assembling a device that when under an axial

force, reacts (transmits) the axial force onto the first tubular

member flange and the secondary flange. Cameron asserts that

“simple logic and a review of the ‘925 patent demonstrate that

this ‘axial force’ would not be present if the wellhead apparatus

were assembled and placed in a box. However, the limitations of

claims 1 and 37 require that the “wellhead assembly” already be

connected to a well, and not lying in a box somewhere. The

device claimed in both claims 1 and 37 includes the limitation of

a casing, which is actually a part of the working well itself and

therefore the claimed device can never be fully assembled in a

box. Rather, when the claimed device is fully assembled at the

well, the device of claims 1 and 37 will inherently be exposed to

the axial force of gravity acting on it in addition to any

pressure applied by the well itself. 

The “wherein” clause of claims 1 and 37 does not require

that a certain type of axial force act on the frac mandrel but

only requires that there is some type of axial force acting on

the frac mandrel. In other words, the requirement of an axial

force merely requires that the wellhead assembly be in an

environment where there is an axial force present and acting on

the frac mandrel. Given that an axial force is present and

acting on the frac mandrel, the wherein clause imports the

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functional limitation that said axial force be reacted in both

the first tubular member flange and the secondary flange. 

Because the “wherein” clause of claims 1 and 37 merely

limits the functionality of the first tubular member flange and

the secondary flange while an axial force is present and acting

on the frac mandrel, it does not constitute a method step as

Cameron contends. Instead, it is more analogous to claims that

use “adapted for” language or conditional language to describe

how an apparatus will behave under certain conditions. 

II. The prosecution history supports the argument that

claims 1 and 37 merely describe how the device

will react when such force inevitably acts on the

device. 

In light of the prosecution history and specification, the

“wherein” clause of claims 1 and 37 is merely a functional

limitation on the structure of the device of claims 1 and 37. 

According to the prosecution history of the Smith ‘194 patent, to

overcome a rejection of claim 1 during prosecution of the '925

patent, Duhn’s patent attorney argued that "if a load were to be

axially acted upon the alleged frac mandrel 34 of Smith, the load

will not be reacted in both the alleged first tubular member

flange and the alleged secondary flange disclosed therein." 

Hence, Duhn differentiated claim 1 from the prior art by arguing

that the language of the "wherein" clause limited claim 1, not by

requiring a method step, but by requiring that "the first tubular

member flange" and "the secondary flange" react in a different

way from the prior art when an axial force is applied. Moreover,

at no point during the prosecution of the '925 patent did the

prosecuting attorney or the Examiner even hint at the possibility

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 Col. 8, line 47 through Col. 9 line 24 of the '596 patent 13

states:

Two compression rings 364 (each similar to one half of the

ring 64 of Fig. 4) separated by a plain ring 365 are retained

within a correspondingly shaped annular, internal recess formed

by the upper and lower section 303, 330. Also, within this recess

is an annular sleeve 301. The sleeve 301 is threaded at 302 onto

a corresponding internal thread on the section 330. Seals 304 are

provided to seal between the sleeve and the section 330.

The sleeve 301 has an upper region which has both an

internally tapered surface 306 and an externally tapered surface.

The upper section 303 has an upper internally tapered surface 308

and a lower internally tapered surface 307.

When the components are assembled as shown in Fig. 9,

32

that claims 1 or 37 require that the wellhead assembly actually

be used in order to meet the subject claim limitation. The

Examiner, like the prosecuting attorney, agreed that the language

of the "wherein" clause of claims 1 and 37 merely places a

functional limitation onto the device being claimed. 

As an example, Duhn Oil argues that during prosecution, the

Examiner rejected what was then claim 72 as being anticipated by

U.S. Patent No. 6,092,596 ("the '596 patent"). (See the Office

action of January 18, 2005 Claim 72 included language identical

to the language of the "wherein" clause of claims 1 and 37.) The

Examiner found that Figure 9 and Col. 8, line 47 through Col. 9,

line 24 of the '596 patent disclosed what was recited in claim 72

including the language of the "wherein" clause. The Examiner

stated that the '596 patent discloses a device "wherein an axial

force acts on the frac mandrel and is reacted in both the first

and second flanges." The language of Col. 8, line 47 through

Col. 9, line 24 of the '596 patent describes structural elements

of a clamping well casing in terms of how those elements will

inherently function when the device is assembled.13

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tightening of the nuts 342 (of which there will be several around

the circumference) draws the upper section 303 towards the lower

section 330. This will cause all the taperng surfaces to ride

over one another.

The surface 308 of the upper section 303 will ride over the

upper compression ring 364 and will compress the ring inwardly. 

The surface 307 of the upper section 303 will ride over the

upper part of the sleeve 301 and will compress the sleeve

inwardly.

At the same time, the upper part of the sleeve 301 will be

driven into the tapering gap between the lower one of the

compression rings 364 and the upper section 303, and this will

cause the lower compression ring to be compressed radially

inwards, to grip the casing hanger 352, at whatever part of the

hanger lies within the circumference of the rings 364.

In this embodiment, metal/metal seals exist between the

surfaces of the upper and lower sections, the compression rings

364 and the sleeve 301. The surfaces of the compression rings

which will make contact with the hanger 352 can be ribbed or

serrated, in order to enhance the grip of the rings on the

hanger. The compression ring could be made from a single

component with two oppositely tapered surfaces, instead of the

construction described above.

The clamping/clamping system described here is easy and

simple to operate and allows the parts of the clamp to be held

apart, against gravitational influences, until the components to

be clamped are in their correct relative positions. It also

allows the clamp to be easily opened and closed to allow

adjustment of relative axial positions.

33

The Examiner cited prior art against the language of the

"wherein" clause of claims 1 and 37, which describes a structure

in terms of functional limitations. Thus, the Examiner, who is

of ordinary skill in the art, understood that the language of the

"wherein" clause of claims 1 and 37 constituted a functional

limitation and not a method step. Therefore, applying the

presumption that the Examiner correctly analyzed the '925

application, it would be incorrect to do as Cameron suggests and

usurp the clear intent of the Applicant and the Examiner. to rewrite the functional limitation of claims 1 and 37 into a method

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step.

III. Whether Duhn Oil’s claim of infringement is

estopped by the Festo and the Doctrine of

Equivalents is not reasonable on claim

interpretation as a matter of law. 

The doctrine of equivalents applies that when the

patentee originally claimed the subject matter alleged to

infringe but then narrowed the claim in response to a rejection;

the patentee may not argue that the surrendered territory

comprised unforseen subject matter that should be deemed

equivalent to the literal claims of the issued patent. Festo v.

Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd, et al, 535 U.S. 722,

733-734 (2002). In some cases the USPTO may have rejected an

earlier version of the patent application on the ground that a

claim does not meet a statutory requirement for patentability. 

Id. at 727. When the patentee responds to the rejection by

narrowing the claims, this prosecution history estops the

patentee from later arguing that the subject matter covered by

the original, broader claim was nothing more than an equivalent. 

Id. Competitors may rely on the estoppel to ensure that their own

devices will not be found to infringe by equivalence. Id. at

727. Prosecution history estoppel ensures that the doctrine of

equivalents remains tied to its underlying purpose. Id. at 734. 

Where the original application once embraced the purported

equivalent but the patentee narrowed the claims to obtain the

patent or to protect its validity, the patentee cannot assert

that the patentee lacked the words to describe the subject matter

in question. Id. at 734. The doctrine of equivalents is

premised on language’s inability to capture the essence of

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innovation, but a prior application describing the precise

element at issue undercuts that premise. Id. at 734. In that

instance the prosecution history has established that the

inventor turned his attention to the subject matter in question,

knew the words for both the broader and narrower claim, and

affirmatively chose the narrower. Id. at 734-735. 

Cameron argues that Duhn Oil inserted the “wherein” clause

of claims 1 and 37 through a narrowing amendment admitted to be

made for “reasons related to patentability.” Cameron claims that

Duhn Oil filed a Petition to Make Special through which it

admitted that it was aware of the construction of the accused

products at the time the amended claims were submitted to the

Patent Office. As a result, Cameron argues that Duhn Oil cannot

rebut the presumption which precludes it from asserting a claim

of infringement under the doctrine of equivalents. However, the

parties have not sufficiently explained what was abandoned to

comply with the examiner’s rejection to permit the application of

the doctrine of equivalents. This is a factual inquiry that will

test whatever design and function the invention now has, to

determine what was rejected or limited by the examiner and

patentee. The issues Cameron raises as well as the issue of how

and with what effect Duhn Oil chose to narrow its claims from

broader language to meet the requirements for patentability,

involve questions of fact that cannot be decided on this record. 

6. CONCLUSION

For the reasons stated above, the following claim

interpretation is made for Plaintiff’s ‘925 patent: 

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• The term “extending from” in claims 1 and 37 is not

limited to products or structures that are mechanically

or structurally connected and includes structures or

products that abut each other. 

• The language of the “wherein” clause of claims 1 and 37

represents a functional limitation and not a method

step.

• The Court cannot determine the applicability of

prosecution estoppel based on the Doctrine of

Equivalents on the existing record.

SO ORDERED.

DATED: February 1, 2007.

/s/ Oliver W. Wanger

____________________________

OLIVER W. WANGER

United States District Judge

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