UNITED STATES DISTRICT COURT FOR THE 

DISTRICT OF NEW HAMPSHIRE

Hypertherm, Inc.

v. Civil No. 05-cv-373-JD

American Torch Tip Company

SEALED ORDER

Hypertherm, Inc. brought a patent infringement action

against American Torch Tip Company (“ATTC”) alleging infringement

of five patents owned by Hypertherm. Hypertherm moves for

summary judgment on ATTC’s affirmative defenses of laches,

estoppel, acquiescence, waiver, and unclean hands. ATTC moves

for summary judgment on Hypertherm’s claim that its products

infringe United States Patent No. 5,310,988 (“the ‘988 patent”)

based on its affirmative defense of estoppel. Hypertherm

challenges the theory and evidence offered by ATTC in support of

its defenses under Federal Rule of Civil Procedure 37(c)(1).

Hypertherm contends in its motion for summary judgment that

ATTC’s affirmative defenses of laches, estoppel, acquiescence,

waiver, and unclean hands are asserted only as to the claims of

infringement of the ‘988 patent. ATTC alleged that “[o]ne or

more of Hypertherm’s causes of action are barred by the doctrines

of laches, estoppel, acquiescence, waiver, or unclean hands.” 

Am. Ans., doc. 39, ¶ 49. In its interrogatory answer, stating

Case 1:05-cv-00373-JD Document 308 Filed 09/11/08 Page 1 of 16
1The interrogatory answer is addressed in more detail below.

2

the basis for its affirmative defenses, and in response to

Hypertherm’s motion, ATTC addresses only the ‘988 patent.1 ATTC

does not dispute Hypertherm’s claim that the affirmative defenses

are limited to the ‘988 patent infringement claims. Therefore,

the affirmative defenses are construed to be asserted against

only the ‘988 patent. 

The ‘988 patent is titled: “Electrode for High Current

Density Plasma Arc Torch.” The patent explains that “[t]he

diameter of a hafnium insert press fit into the bottom end of a

copper electrode varies as a function of the level of current

carried by the electrode [and] is the minimum necessary to

support emission at that current level while also protecting the

copper body against attack by the arc.” ‘988 Patent, Abstract.

The ‘988 patent pertains to an electrode and a method of

operation for a high definition plasma arc cutting torch that

uses an insert of hafnium or another similar material and a

method for cooling the insert to extend the life of the

electrode. ‘988 patent, col. 6.

Case 1:05-cv-00373-JD Document 308 Filed 09/11/08 Page 2 of 16
2ATTC served its answers the day after the close of fact

discovery so that discovery was not ongoing at that time.

3

I. Exclusion under Rule 37(c)(1)

In the course of discovery, Hypertherm propounded an

interrogatory asking ATTC to “[s]tate in detail the basis for

[its] contention, as set forth in its affirmative defenses, that

one or more of Hypertherm’s causes of action are barred by the

doctrines of laches, estoppel, acquiescence, waiver, and/or

unclean hands, including all facts, information, and documents

that ATTC’s [sic] asserts support or are pertinent to ATTC’s

contention.” Doc. no. 204-4, Interrogatory 23, at 14. ATTC

answered: 

With respect to the ‘988 patent, since at least 1998 or

1999, ATTC and Hypertherm have several times discussed

the size of hafnium inserts for ATTC electrodes to

which Hypertherm would not object. For example, in

communications with John D. Walters III and Michael

Golden in or around 1999, Hypertherm agreed with ATTC

that ATTC’s use of hafnium having diameters of .028

inches for 15 amp and 30 amp electrodes, and .040 for

50 amp and 70 amp electrodes would not infringe claims

of the ‘988 patent. In other instances, pursuant to

the agreement of the parties, Hypertherm has reviewed

catalogs of ATTC’s products, including with specific

reference to the ‘988 patent, with the understanding

that Hypertherm would notify ATTC of any objections to

any products advertised in those catalogs, and

Hypertherm has not objected to the size of the hafnium

inserts in ATTC’s electrodes. 

Id. at 14-15. ATTC further stated that discovery was ongoing and

reserved the right to supplement its response.2 Hypertherm

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represents, and ATTC does not dispute, that ATTC did not

supplement its answer to the interrogatory.

For purposes of the motions for summary judgment, however,

ATTC contends that its affirmative defenses are based on events

that began with an exchange of letters between Hypertherm’s

counsel and ATTC during the fall of 1996. ATTC cites a letter

from Hypertherm to ATTC dated October 8, 1996, which accused two

of ATTC’s electrodes, part numbers 120111 and 120112, of

infringing the ‘988 patent, and ATTC’s response in a letter dated

October 28, 2006, in which ATTC stated that it would like to

comply with the ‘988 patent and would, therefore, use a larger

hafnium insert. ATTC argues that Hypertherm was then silent

about infringement of the ‘988 patent until just before this suit

was filed in 2005. 

Hypertherm contends that ATTC is barred under Rule 37(c)(1)

from relying on the new theory, based on communications in 1996,

because ATTC did not disclose that basis for its affirmative

defenses in response to Hypertherm’s interrogatory asking for

that information. ATTC contends that Rule 37(c)(1) does not

apply because the 1996 letters were disclosed in the course of

other discovery.

Unless a procedural issue is unique to patent law, the law

of the regional circuit that governs the district court applies. 

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Wilson Sporting Goods Co. v. Hillerich & Bradsby Co., 442 F.3d

1322, 1325-26 (Fed. Cir. 2006). Discovery matters are generally

not unique to patent law. See Group One, Ltd. v. Hallmark Cards,

Inc., 407 F.3d 1297, 1307 (Fed. Cir. 2005); Anchor Wall Sys.,

Inc. v. Rockwood Retaining Walls, Inc., 340 F.3d 1298, 1313 (Fed.

Cir. 2003) (discovery sanctions not unique). Therefore, the law

of the First Circuit applies here. 

Rule 37(c)(1) provides that if a party fails to provide

information that is required by Rule 26(e), “the party is not

allowed to use that information . . . to supply evidence on a

motion . . . unless the failure was substantially justified or is

harmless.” Under Rule 26(e), 

[a] party . . . who has responded to an interrogatory .

. . must supplement or correct its disclosure or

response: [] in a timely manner if the party learns

that in some material respect the disclosure or

response is incomplete or incorrect, and if the

additional or corrective information has not otherwise

been made known to the other parties during the

discovery process or in writing . . . .

The purpose of Rule 26(e)’s supplementation requirement is to

“increase[] the quality and fairness of the trial by narrowing

the issues and eliminating surprise.” Colon-Millin v. Sears

Roebuck de P.R., 455 F.3d 30, 37 (1st Cir. 2006) (internal

quotation marks omitted). Therefore, if a party changes its

theory of the case from the theory previously stated in an

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interrogatory answer, it is obligated under Rule 26(e) to

supplement its answer. Id. at 38-39. 

In this case, ATTC stated in its interrogatory answer that

its affirmative defenses were based on communications beginning

in 1998 or 1999. For purposes of summary judgment, however, it

contends that its defenses are based on events starting with the

1996 letters. Although the 1996 letters were disclosed through

other discovery, ATTC does not explain the context in which the

disclosures occurred or whether it notified Hypertherm of the

import of the 1996 letters to its theory of the affirmative

defenses. 

ATTC has not shown that it complied with the requirements of

Rule 26(e) by disclosing the 1996 letters during other discovery. 

Although a late disclosure also may avoid sanctions under Rule

37(c) in appropriate circumstances, ATTC makes no developed

argument that the delay was substantially justified or harmless. 

See Gagnon v. Teledyne Princeton, Inc., 437 F.3d 188, 191 (1st

Cir. 2006). Therefore, ATTC is barred from using the 1996

letters to support its affirmative defenses of laches, estoppel,

acquiescence, waiver, and unclean hands.

As is discussed below, however, even if ATTC were able to

rely on the 1996 letters to support its affirmative defenses, the

record would not prevent summary judgment in favor of Hypertherm.

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II. Summary Judgment Motions

Hypertherm seeks summary judgment in its favor on ATTC’s

affirmative defenses of laches, estoppel, acquiescence, waiver,

and unclean hands. ATTC seeks summary judgment in its favor on

Hypertherm’s infringement claims under the ‘988 patent on the

ground that Hypertherm is equitably estopped from claiming

infringement.

Summary judgment is appropriate when “the pleadings, the

discovery and disclosure materials on file, and any affidavits

show that there is no genuine issue as to any material fact and

that the movant is entitled to judgment as a matter of law.” 

Fed. R. Civ. P. 56(c). The party seeking summary judgment must

first demonstrate the absence of a genuine issue of material fact

in the record. See Celotex Corp. v. Catrett, 477 U.S. 317, 323

(1986). A party opposing a properly supported motion for summary

judgment must present competent evidence of record that shows a

genuine issue for trial. See Anderson v. Liberty Lobby, Inc.,

477 U.S. 242, 256 (1986). All reasonable inferences and all

credibility issues are resolved in favor of the nonmoving party. 

See id. at 255. 

When parties file cross motions for summary judgment, “the

court must evaluate each motion on its own merits, taking care in

each instance to view the evidence in favor of the nonmoving

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party.” Cross Med. Prods., Inc. v. Medtronic Sofamor, 424 F.3d

1293, 1302 (Fed. Cir. 2005) (internal quotation marks omitted).

“[T]he fundamental premise of a grant of summary judgment is that

no reasonable jury could find other than in favor of the movant.” 

Gemmy Indus. Corp. v. Chrisha Creations Ltd., 452 F.3d 1353, 1359

(Fed. Cir. 2006).

A. Hypertherm’s Motion

Hypertherm moves for summary judgment on ATTC’s affirmative

defenses of laches, estoppel, acquiescence, waiver, and unclean

hands on the grounds that ATTC lacks evidence to support the

defenses. As is discussed above, because ATTC failed to

supplement its interrogatory answer pertaining to the basis for

its affirmative defenses, it is barred from using evidence of the

1996 letters. ATTC offers little else in support of its

affirmative defenses and its opposition to Hypertherm’s motion. 

Even if the excluded evidence were considered, however, ATTC

cannot show that a factual dispute exists to support its

defenses.

1. Estoppel

To avoid a patent infringement claim based on the defense of

equitable estoppel, the alleged infringer must prove all three

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elements of the defense by a preponderance of the evidence. 

Vanderlande Indus. Nederland BV v. I.T.C., 366 F.3d 1311, 1324

(Fed. Cir. 2004). The three elements of estoppel are: “1) the

patentee, through misleading conduct, leads the alleged infringer

to reasonably infer that the patentee does not intend to enforce

its patent against the alleged infringer, 2) the alleged

infringer relies on that conduct, and 3) due to its reliance, the

alleged infringer will be materially prejudiced if the patentee

is allowed to proceed with its claim.” Ecolab, Inc. v.

Envirochem, Inc., 264 F.3d 1358, 1371 (Fed. Cir. 2001).

ATTC argues that Hypertherm mislead it into reasonably

inferring that Hypertherm would not enforce the ‘988 patent as to

ATTC’s electrodes based on the 1996 communications and the lack

of adverse actions until 2005. As related by ATTC, when

Hypertherm accused ATTC of infringing the ‘988 patent in October

of 1996 through part numbers 12011 and 120112, it responded with

a plan to design around the ‘988 patent and Hypertherm did not

respond. Thereafter, it produced products numbered 120111 and

120112 with larger hafnium inserts that it thought avoided

infringement. Hypertherm tested those products in January of

1997 and reviewed certain pages of ATTC’s product catalogs

without notifying ATTC that the 120111 and 120112 parts were

infringing the ‘988 patent.

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The version of the parties’ interactions recited by ATTC

omits an important event, however. On October 25, 1996,

Hypertherm brought suit against ATTC and a related company,

Plasma Components, Inc., alleging infringement of eight patents. 

Hypertherm accused Plasma Components, Inc. of infringing the ‘988

patent and accused ATTC of infringing other Hypertherm patents. 

The parties settled the case through an agreement signed on May

21, 1997. 

As part of the settlement, ATTC and Plasma agreed to destroy

certain “non-genuine replacement parts,” including the 120111 and

120112 parts, which were listed as Plasma parts. In addition,

the agreement allowed ATTC and Plasma to offer for sale some

products as alternatives to genuine Hypertherm replacement parts,

including the 120111 and 120112 parts, as long as they were

labeled “120111ATTC” and “120112ATTC.” 

Hypertherm’s 1996 patent infringement action, asserting

infringement of the ‘988 patent along with other Hypertherm

patents, involved the 120111 and 120112 parts that it had accused

in the October 8, 1996, letter to ATTC. The suit resulted in a

settlement that specifically addressed the 120111 and 120112

parts. Therefore, Hypertherm did not mislead ATTC to infer,

reasonably, that its effort to design the 120111 and 120112 parts

to avoid infringement of the ‘988 patent was successful.

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ATTC has not shown that a material factual dispute exists as

to the elements of equitable estoppel. The record shows that

Hypertherm defended the ‘988 patent and is not equitably estopped

from accusing ATTC of infringing the ‘988 patent. Therefore,

Hypertherm is entitled to summary judgment on that defense.

2. Laches and Acquiescence

Laches and acquiescence are related defenses that apply when

a patent holder delays bringing suit, intentionally or

inadvertently. Cabot Safety Intermediate Corp. v. Arkon Safety

Equip., Inc., 979 F. Supp. 929, 931 (D. Mass. 1997); see also

Sch. Union No. 37 v. Ms. C., 518 F.3d 31, 35 (1st Cir. 2008). To

prove laches, the defendant “must prove: (1) that the plaintiff

delayed filing suit for an unreasonable and inexcusable length of

time from the time the plaintiff knew or reasonably should have

known of its claim against the defendant, and (2) that the delay

operated to the prejudice or injury of the defendant.” Symantex

Corp. v. Computer Assocs. Int’l, Inc., 522 F.3d 1279, 1294 (Fed.

Cir. 2008) (internal quotation marks omitted). A presumption of

laches arises if the defendant shows a delay of more than six

years after the plaintiff had actual or constructive knowledge of

the defendant’s allegedly infringing activity. Id. To prove

acquiescence, the defendant must prove that the plaintiff’s

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conduct amounted to an assurance that the plaintiff would not

assert a claim of patent infringement against the defendant and

that the plaintiff unreasonably delayed action causing prejudice

to the defendant. See Creative Gifts, Inc. v. UFO, 235 F.3d 540,

547-48 (10th Cir. 2000) (acquiescence in context of trademark

litigation); Kellogg Co. v. Exxon Corp., 209 F.3d 562, 569 (6th

Cir. 2000) (same). 

ATTC contends that Hypertherm is barred by the doctrines of

laches and acquiescence from bringing its infringement claims

under the ‘988 patent. In support of its defense, ATTC asserts

that Hypertherm first raised the issue of infringement of the

‘988 patent in the October 8, 1996, letter, and then was silent

on the issue until 2005 when it filed this patent infringement

action. ATTC further asserts that it continued to manufacture

and sell its “design around” electrodes, believing that they did

not infringe the ‘988 patent.

As is discussed in the context of estoppel, Hypertherm was

not silent for the nine years between the October 1996 letter and

filing suit in this case. Instead, Hypertherm brought a patent

infringement suit in 1996 against ATTC and its related company,

Plasma Components, asserting infringement of the ‘988 patent by

the same parts that were referenced in the October 1996 letter. 

That litigation concluded with a settlement agreement in 1997. 

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Based on the record, ATTC cannot show that Hypertherm inexcusably

and unreasonably delayed in filing this suit or that Hypertherm

provided any express or implied assurance that it would not

enforce the ‘988 patent against ATTC. Hypertherm is entitled to

summary judgment on the affirmative defenses of laches and

acquiescence.

3. Waiver

ATTC also asserts that Hypertherm waived its patent

infringement claims under the ‘988 patent. “‘A waiver is

ordinarily an intentional relinquishment or abandonment of a

known right or privilege.’” Harris Corp. v. Ericsson Inc., 417

F.3d 1241, 1263 n.2 (quoting Johnson v. Zerbst, 304 U.S. 458, 464

(1938)). ATTC points to nothing in the record that shows a

factual dispute as to whether Hypertherm waived its right to

protect the ‘988 patent. Therefore, Hypertherm is entitled to

summary judgment on the affirmative defense of waiver.

4. Unclean Hands

The doctrine of unclean hands provides an equitable defense

against claims “where some unconscionable act of one coming for

relief has immediate and necessary relation to the equity that

[the party] seeks in respect of the matter in litigation.” 

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Keystone Driller Co. v. Gen. Excavator Co., 290 U.S. 240, 245

(1933); accord Consol. Alum. Corp. v. Foseco Int’l Ltd., 910 F.2d

804, 810 (Fed. Cir. 1990). Hypertherm contends that ATTC lacks

evidence of any unconscionable activity or fraudulent act

involving the ‘988 patent to support its defense. ATTC supports

its defense of “unclean hands” by asserting that it “maintains

viable counterclaims against Hypertherm, including antitrust

claims arising out of the Sherman Act,” which it contends would

constitute unconscionable activity.

To oppose a motion for summary judgment, however, the

nonmoving party must submit competent evidence to rebut the

motion. Kearney v. Town of Wareham, 316 F.3d 18, 22 (1st Cir.

2002). Mere assertions by counsel made in a memorandum are not

enough to avoid summary judgment. Fed. Refinance Co., Inc. v.

Klock, 352 F.3d 16, 31 (1st Cir. 2003); Vivid Techs., Inc. v. Am.

Science & Eng’g, Inc., 200 F.3d 795, 812 (Fed. Cir. 1999). The

opposing party also cannot rely on allegations made in a pleading

to avoid summary judgment. Fed. R. Civ. P. 56(e). 

ATTC’s argument that it has stated a claim for an antitrust

violation in its counterclaim is not competent to oppose

Hypertherm’s motion for summary judgment. In the absence of any

evidence of unclean hands, Hypertherm is entitled to summary

judgment on that defense.

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III. ATTC’s Motion for Summary Judgment

ATTC moves for summary judgment in its favor on Hypertherm’s

infringement claims under the ‘988 patent. ATTC contends that

the doctrine of equitable estoppel bars Hypertherm’s claims. In

support of its motion, ATTC relies on the same evidence it

offered to oppose Hypertherm’s motion, including the 1996 letters

that were not disclosed in response to Hypertherm’s interrogatory

to explain the basis of its affirmative defenses. That evidence

has been excluded under Rule 37(c)(1).

Even if the evidence were considered, however, as is

explained in granting Hypertherm’s motion for summary judgment on

ATTC’s affirmative defense of equitable estoppel, ATTC did not

provide evidence that Hypertherm engaged in misleading conduct

that lead ATTC to reasonably infer that Hypertherm would not

enforce the ‘988 patent. Therefore, ATTC cannot sustain its

burden of proof for purposes of achieving summary judgment in its

favor.

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Conclusion

For the foregoing reasons, the plaintiff’s motion for

summary judgment (document no. 204) is granted. The defendant’s

motion for summary judgment (document no. 200) is denied. The

defendant’s affirmative defenses of laches, estoppel,

acquiescence, waiver, and unclean hands are dismissed.

SO ORDERED.

____________________________

Joseph A. DiClerico, Jr.

United States District Judge

September 11, 2008

cc: Jill C. Anderson, Esquire

Jacob K. Baron, Esquire

Steven M. Bauer, Esquire

Lucas M. Blower, Esquire

Seth M. Cannon, Esquire

Joseph A. Capraro, Jr., Esquire

Jeffery M. Cross, Esquire

Joseph T. Dattilo, Esquire

Ami D. Gandhi, Esquire

Maia H. Harris, Esquire

Marc H. Kallish, Esquire

Rhett R. Krulla, Esquire

Jonathan A. Lax, Esquire

Richard C. Nelson, Esquire

W. Scott O'Connell, Esquire

Jeremy P. Oczek, Esquire

Richard D. Rochford, Jr., Esquire

John M. Skeriotis, Esquire

Benjamin M. Stern, Esquire

Wayne Tang, Esquire

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