UNITED STATES DISTRICT COURT FOR THE 

DISTRICT OF NEW HAMPSHIRE

Hypertherm, Inc.

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

American Torch Tip Company

O R D E R

Hypertherm, Inc. alleges that certain replacement parts

manufactured and sold by American Torch Tip Company (“ATTC”)

infringe five of Hypertherm’s patents, United States Patents No.

7,019,255 (“‘255 patent), No. 6,946,617 (“‘617 patent”), No.

6,207,923 (“’923 patent”), No. 5,977,510 (“‘510 patent”), and No.

5,310,988 (“‘988 patent”). ATTC denies that its products

infringe and also asserts that several of the patents are invalid

due to obviousness. Hypertherm moves to preclude the testimony

of ATTC’s expert witness, James Sprague, on the ground that he is

not qualified to give opinions on infringement or obviousness. A

hearing was held on Hypertherm’s motion on February 24, 2009.

Standard of Review

A witness may give opinion testimony at trial if technical

knowledge will assist the factfinder and if the “witness is

qualified as an expert by knowledge, skill, experience, training,

or education . . . .” Fed. R. Evid. 702. A qualified expert may

Case 1:05-cv-00373-JD Document 515 Filed 02/27/09 Page 1 of 14
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testify in the form of opinions “if (1) the testimony is based

upon sufficient facts or data, (2) the testimony is the product

of reliable principles and methods, and (3) the witness has

applied the principles and methods reliably to the facts of the

case.” Id. “The court, in its role as gatekeeper, must exclude

expert testimony that is not reliable and not specialized, and

which invades the province of the jury to find facts and that of

the court to make ultimate legal conclusions.” Sundance, Inc. v.

DeMonte Fabricating Ltd., 550 F.3d 1356, 1364 (Fed. Cir. 2008). 

To testify as a technical expert on issues of patent

infringement and invalidity, the witness must be “qualified as an

expert in the pertinent art.” Id. at 1363; see also Levin v.

Dalva Bros., Inc., 459 F.3d 68, 78-79 (1st Cir. 2006) (excluding

expert’s opinion identifying antique clock because witness lacked

experience in authenticating furniture of particular era through

visual examination). The proponent of expert testimony bears the

burden of showing, by a preponderance of the evidence, that the

expert is qualified under Rule 702. See Fed. R. Evid. 104(a);

Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 592 n.10

(1993).

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Background

In the specifications of the five patents in suit, the field

of invention is described, generally, as “plasma arc torch

systems and processes,” “plasma arc cutting torches,” or “plasma

arc torches.” More specifically, the ‘617 and ‘255 patents

relate to “liquid cooled electrodes and coolant tubes for use in

a plasma arc torch.” The ‘988 patent relates “to an improved

electrode and insert cooling method for use in low current, high

definition torches.” The ‘510 patent relates “to an improved

nozzle for use in plasma arc torches,” and the ‘923 patent

relates “to plasma arc torches having a torch tip designed to

produce a substantially columnar shield flow that surrounds the

plasma arc without substantially interfering with the plasma

arc.” 

James Sprague holds a Ph.D. in mechanical engineering. He

has work experience at Goodyear Tire and Rubber Company designing

air springs, conveyor belting, racing tires, testing equipment,

and manufacturing machines. He has additional experience in

dynamic simulation of mechanisms and code enhancement for

simulation software; and in design and analysis of machines,

mechanisms, and vehicles. He has worked in the areas of machine

testing and machine failure and in accident reconstruction. He

has lectured in mechanical engineering and has taken a course in

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forensic engineering. He is currently employed as vice president

at Packer Engineering, Inc., which provides engineering

consultant services.

At the hearing, Sprague explained that he prepared for his

role as an expert witness in this case by studying the patents in

suit until he understood the relationships of the parts and what

was described in the patents. Sprague described certain

electrodes and related parts, which were introduced as exhibits. 

He also noted the particular problems the inventions were

designed to address. 

Sprague acknowledged, and ATTC concedes, that he has no

experience or training in plasma arc cutting torches or their

consumable parts. He has no experience or training in plasma arc

technology. Instead, Sprague based his opinions on patent

infringement and invalidity by gaining an understanding of the

patents through reading and studying them, which was informed by

his background in basic mechanical engineering principles, such

as geometry, fluid flow, and heat transfer. He also reviewed

materials provided to him by counsel for ATTC. Based on that

background, Sprague offers opinions that ATTC’s accused products

do not infringe the patents in suit and that certain of the

inventions would have been obvious at the time the patents

issued, making the patents invalid. 

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Hypertherm called Aaron Brandt, who is an engineer at

Hypertherm and a named inventor of the ‘255 and ‘617 patents, to

testify at the hearing about the level of skill required to work

at the engineering level in the field of plasma arc torches and

cutting systems. Brandt was allowed to testify, over ATTC’s

objection, about the education and experience of those who work

with him in the field of plasma arc torch technology. 

Brandt testified that he and the other inventors of the

patents in suit had engineering degrees, some with advanced

degrees, including Ph.D.s in plasma physics. All of the

inventors had at least several years of experience in the field

of plasma cutting technology and some had as much as twenty years

of experience. Brandt testified that he had a master’s degree in

mechanical engineering with a focus in fluid mechanics and a

background in laser cutting when he began work at Hypertherm. 

Despite that background, it took him fourteen months of work to

become familiar with plasma arc technology. 

Brandt described the problems encountered in plasma arc

cutting systems and the processes his engineering team used to

invent new technology. The engineering problems in plasma arc

cutting systems include the high temperatures, high current, and

high voltage involved in the systems. Given those circumstances,

alignment of various parts is challenging where close alignment

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may increase the life of the part but the high voltage requires

more space. On cross examination, Brandt explained that the

physics involved in plasma arc torches is specific to the

technology, noting that fluid mechanics differs from plasma

mechanics. 

Discussion

ATTC contends that its witness, James Sprague, is qualified,

based on his education and experience in mechanical engineering,

to give opinions on patent infringement and obviousness in this

case. ATTC also asserted at the hearing that Hypertherm’s motion

challenging Sprague’s qualifications was untimely and failed to

notify ATTC that it would also challenge Sprague’s methodology. 

Hypertherm argues that Sprague lacks the necessary background in

plasma arc torches and cutting systems to be qualified as an

expert on the patents and products at issue in this case. 

I. Challenges to Motion

ATTC asserts that Hypertherm’s motion to preclude Sprague’s

testimony was untimely and also objected to Hypertherm’s

examination, at the hearing, of Sprague’s methodology. The

scheduling order in this case required the parties to file

motions challenging expert testimony forty-five days before

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1Although the trial date has been continued to April 27,

2009, all of the deadlines counted from the trial date or the

final pretrial conference date are based on the February 18,

2009, trial date. The continuance of the trial does not extend

the time for the parties to file pretrial motions.

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trial. Trial was scheduled for February 18, 2009.1 Therefore,

forty-five days prior to trial was January 5, 2009. See Fed. R.

Civ. P. 6(a). Hypertherm’s motion challenging Sprague’s

testimony was filed on January 5, 2009. Therefore, it was timely

filed. See also Feliciano-Hill v. Principi, 439 F.3d 18, 24 (1st

Cir. 2006) (holding that parties have an obligation to object to

an expert in a timely fashion, that is, before trial).

ATTC also objected at the hearing that Hypertherm had not

challenged Sprague’s methodology in its motion and should not be

permitted to question Sprague about methodology. In its motion,

Hypertherm argued that Sprague’s opinion of invalidity of the

‘988 patent was not admissible because it was based on counsel’s

representations and Sprague’s unfounded assumptions. Because

ATTC is correct that Hypertherm did not raise methodology as a

general basis to exclude Sprague’s opinions, consideration of 

methodology is limited to the issue raised in the motion.

The primary issue is whether Sprague is qualified by his

knowledge, skill, experience, training, or education to give

opinions on infringement and validity of the patents in suit.

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2At the hearing, counsel for ATTC mistakenly characterized

the holding in Sundance as affirming the district court’s

decision to preclude the defendant’s expert from testifying on

technical matters because the expert was not disclosed as a

technical expert. Counsel then represented that the Federal

Circuit’s discussion of expert qualifications was merely dicta. 

The court will assume that counsel’s mistake was due to a less

than thorough reading of the case.

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II. Qualification

The Federal Circuit recently addressed the standard for

qualifying a technical expert witness to testify on patent

infringement and validity. In Sundance, the plaintiff charged

the defendant with infringing claim 1 of its patent for

“retractable segmented covering systems.” 550 F.3d at 1358. The

defendant disclosed an expert witness, who was a patent lawyer

and had practiced only briefly as an engineer, to testify about

Patent Office practices, claim construction, noninfringement,

invalidity, and inequitable conduct. Id. at 1360-61. The

plaintiff objected to the witness’s testimony at trial on issues

of infringement and invalidity on the ground that he was not

qualified to testify as a technical expert. Id. The district

court, however, allowed the expert testimony.

On appeal, the Federal Circuit held that, contrary to the

district court’s decision, the witness was not qualified to

testify on the issues of infringement or validity.2 Id. at 1361. 

The court noted that the issues of infringement and validity “are

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3Similarly, in Centricut, LLC v. Esab Group, LLC, 390 F.3d

1361 (Fed. Cir. 2004), a case involving infringement of a patent

pertaining to a plasma arc torch electrode, proof of infringement

required showing that the accused electrode met the work function

claim in the asserted patent. Work function was defined as “the

potential step, measured in electron volts, which permits

thermionic emission from the surface of a metal at a given

temperature.” Id. at 1364 (internal quotation marks omitted). 

The patent holder, Esab, offered the testimony of the patent

inventor to prove infringement. Id. at 1368. The inventor,

however, admitted that he was not an expert on work function, and

therefore, the court did not credit his testimony. Id.

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analyzed in great part from the perspective of a person of

ordinary skill in the art, and testimony explaining the technical

evidence from that perspective may be of great utility to the

factfinder.” Id. In contrast, the court found that the

defendant’s witness had “no experience whatsoever in the field of

tarps or covers” and that the defendant failed to show that the

witness’s “experience with engines and the like is sufficiently

related to covers.” Id. at 1362. The court stated that

“[a]dmitting testimony from a person such as [the witness], with

no skill in the pertinent art, serves only to cause mischief and

confuse the factfinder.” Id. In conclusion, the court stated: 

“We hold that it is an abuse of discretion to permit a witness to

testify as an expert on the issues of noninfringement or

invalidity unless that witness is qualified as an expert in the

pertinent art.”3

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A. Pertinent Art

ATTC contends that the pertinent art for purposes of

qualifying an expert to testify on invalidity and infringement of

the patents in this case is the consumable parts that are the

subject matter of the patents in suit and that the relevant

technological field is mechanical engineering as it relates to

the design and manufacture of consumable parts. ATTC further

contends that “[t]his technological field is analogous to that of

spare parts for cars.” Hypertherm defines the pertinent art as

plasma arc torch and consumable technology and plasma arc cutting

technology.

In Sundance, the Federal Circuit described the pertinent art

as tarps or covers and cover systems, based on the subject of the

patent claims. 550 F.3d at 1362. In Centricut, the pertinent

art was the work function of electrode components, as claimed in

the patent. 390 F.3d at 1368. Here, the patents describe the

field of the invention generally, as “plasma arc torch systems

and processes,” “plasma arc cutting torches,” or “plasma arc

torches.” The patents also describe the pertinent art more

specifically as “liquid cooled electrodes and coolant tubes for

use in a plasma arc torch,” “an improved electrode and insert

cooling method for use in low current, high definition torches,” 

“an improved nozzle for use in plasma arc torches,” and “plasma

Case 1:05-cv-00373-JD Document 515 Filed 02/27/09 Page 10 of 14
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arc torches having a torch tip designed to produce a

substantially columnar shield flow that surrounds the plasma arc

without substantially interfering with the plasma arc.” 

Therefore, based on the patents themselves, the pertinent

art is liquid cooled electrodes used in plasma arc torches, an

insert cooling method used in low current, high definition plasma

arc torches, nozzles for plasma arc torches, and plasma arc torch

tip design. More generally, the pertinent art is plasma arc

torch systems and processes. 

B. James Sprague

As demonstrated by his curriculum vitae and his testimony at

the hearing, Sprague holds a Ph.D. in mechanical engineering and

has worked in various aspects of mechanical engineering for

twenty-five years. Neither his education nor his experience in

the field of mechanical engineering has included the design or

manufacture of plasma arch torches or any of their consumable

parts, such as electrodes. Sprague, admittedly, has no

experience or training in the field of plasma arc torches or the

consumable parts at issue in this case. The basis of Sprague’s

opinions on the issues of patent infringement and validity is his

knowledge of the principles of mechanical engineering and his

understanding of the patents in suit derived from reading and

Case 1:05-cv-00373-JD Document 515 Filed 02/27/09 Page 11 of 14
4ATTC also attempts to bolster Sprague’s credentials by

comparing him to Hypertherm’s technical expert witness, E. Smith

Reed, who had only a bachelor’s degree in mechanical engineering

when he began working at Centricut, a company that designed and

manufactured consumable parts for plasma arc torches. ATTC

states that after working at Centricut for under four years, Reed

was able to re-engineer and design consumable parts, which ATTC

contends shows that no special knowledge or experience is

necessary for expertise in the field of torch consumables. 

Reed’s experience working in the plasma torch field, however,

distinguishes him from Sprague, who has no experience. 

5Even if they were deemed to be applicable for measuring the

qualifications of a technical expert witness, it is not necessary

here to consider the factors used to determine the hypothetical

person with ordinary skill in the art, which is part of an

obviousness analysis. See, e.g., Ruiz v. A.B. Chance Co., 234

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studying the patents themselves and from materials provided to

him by counsel.

ATTC argues that Sprague’s level of education in mechanical

engineering and his extensive experience in mechanical design of

machine tools and in parts fabrication provide a sufficient basis

for his expertise in this case.4 The complexity of the

technology of plasma arc torches and their consumable parts is

apparent from the patents themselves, from examination of a

cutaway view of a torch, and from the component parts provided by

ATTC and described by Sprague at the hearing. Given the complex

technology, ATTC has not shown that Sprague’s general mechanical

engineering background qualifies him as one who is skilled in the

pertinent art of plasma arc torches and their consumable parts.5

Case 1:05-cv-00373-JD Document 515 Filed 02/27/09 Page 12 of 14
F.3d 654, 666-67 (Fed. Cir. 2000)

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In addition, at the hearing, Sprague had difficulty

recalling the opinions he expressed in his report. When asked

about his opinion on obviousness, he testified that there were

many legal opinions in his report and that he was not comfortable

“reciting” those opinions without reading from the report. When

asked about his opinion on infringement, he again said he was not

comfortable stating his opinion on infringement without referring

to his report and was not willing to summarize his opinion. 

Sprague’s apparent lack of familiarity with his own opinions

undermines the understanding he claims to have of the pertinent

art and the subjects at issue in this case.

Based on the record presented for purposes of evaluating

Sprague’s qualifications to testify under Rule 702, ATTC has not

shown that Sprague is skilled in the pertinent art of plasma arc

torches and their parts, which are at issue in the patents in

suit. A witness will not be permitted to testify as a technical

expert on the issues of patent infringement and validity unless

he is shown to be skilled in the pertinent art. Therefore,

Sprague will not be permitted to testify at trial as a technical

expert on the issues of patent infringement and validity.

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Conclusion

For the foregoing reasons, the plaintiff’s motion to

preclude the testimony of the defendant’s technical expert

witness (document no. 401) is granted.

SO ORDERED.

 /s/Joseph A. DiClerico. Jr.___

Joseph A. DiClerico, Jr.

United States District Judge

February 27, 2009

cc: Jill C. Anderson, Esq. 

Jacob K. Baron, Esq. Richard C. Nelson, Esq. 

Steven M. Bauer, Esq. W. Scott O'Connell, Esq. 

Lucas M. Blower, Esq. Jeremy P. Oczek, Esq. 

Colin G. Cabral, Esq. Richard D. Rochford, Jr., Esq. 

Seth M. Cannon, Esq. David W. Ruoff, Esq. 

Joseph A. Capraro, Jr., Esq. John T. Shapiro, Esq. 

Christopher J. Carney, Esq. John M. Skeriotis, Esq. 

Jeffery M. Cross, Esq. Benjamin M. Stern, Esq. 

Joseph T. Dattilo, Esq. Wayne Tang, Esq. 

Maia H. Harris, Esq. 

Marc H. Kallish, Esq. 

Rhett R. Krulla, Esq. 

Jonathan A. Lax, Esq. 

Edward F. McCormack, Esq. 

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