Document ID: s3://data.kl3m.ai/documents/govinfo/USCOURTS/USCOURTS-ca13-14-05082/USCOURTS-ca13-14-05082-0/pdf.json

Parties Involved:
United States
Appellee
Zoltek Corporation
Appellant

Document Text:

United States Court of Appeals 

for the Federal Circuit ______________________ 

ZOLTEK CORPORATION,

Plaintiff-Appellant

v.

UNITED STATES,

Defendant-Appellee

______________________ 

2014-5082

______________________ 

Appeal from the United States Court of Federal 

Claims in No. 1:96-cv-00166-EJD, Judge Edward J. 

Damich.

______________________ 

Decided: February 19, 2016 

______________________ 

DEAN A. MONCO, Wood, Phillips, Katz, Clark & Mortimer, Chicago, IL, argued for plaintiff-appellant. Also 

represented by JOHN S MORTIMER; MEREDITH MARTIN 

ADDY, Katten Muchin Rosenman LLP, Chicago, IL. 

GARY LEE HAUSKEN, Commercial Litigation Branch, 

Civil Division, United States Department of Justice,

Washington, D.C., argued for defendant-appellee. Also 

represented by DAVID M. RUDDY, JOYCE R. BRANDA, JOHN 

FARGO. 

 _____________________ 

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 2 ZOLTEK CORP. v. US

Before NEWMAN, CLEVENGER, and MOORE, Circuit Judges.

NEWMAN, Circuit Judge. 

Zoltek Corporation seeks compensation from the 

United States for use, with the authorization and consent 

of the Departments of the Air Force and Navy, of the 

patented method of producing carbon fiber sheet products 

as claimed in United States Reissue Patent No. Re 34,162 

issued January 19, 1993 (“the ’162 patent”). The ’162 

patent is a reissue of U.S. Patent No. 4,728,395, issued 

March 1, 1988 to inventor George Boyd and assigned to 

Mr. Boyd’s employer Stackpole Fibers Company. The 

patent was acquired by Zoltek Corporation with its acquisition of Stackpole in 1988. 

Litigation history

On March 25, 1996, Zoltek filed suit in the United 

States Court of Federal Claims (CFC) alleging that the

process used to produce carbon fiber sheet materials for 

the B-2 Bomber and the F-22 Fighter Plane infringed the 

’162 patent. This is the third appeal in this action. The 

factual background is set forth in the prior opinions of the 

CFC and this court.

In the first appeal, this court answered a certified 

question to hold that the patentee has no cause of action 

against the United States when any step of the patented 

method is practiced outside of the United States, as for 

the F-22 Fighter. Zoltek Corporation v. United States, 

442 F.3d 1345, 1353 (Fed. Cir. 2006) (Plager, J., dissenting) (Zoltek I).

On remand, the CFC granted Zoltek’s request for 

leave to amend its complaint to substitute as defendant 

Lockheed Martin, the general contractor for the F-22 

Fighter, and then granted Zoltek’s motion to transfer the

count relating to the F-22 Fighter to the United States 

District Court for the Northern District of Georgia, where 

it was “reasonably plausible” that the court had jurisdicCase: 14-5082 Document: 50-2 Page: 2 Filed: 02/19/2016
ZOLTEK CORP. v. US 3

tion over an infringement suit against Lockheed. Zoltek

Corporation v. United States 85 Fed. Cl. 409, 422 (2009). 

On Lockheed’s motion, this aspect was certified for appeal.

The Federal Circuit then acted en banc (in part) and

reversed its ruling in Zoltek I. This court recognized the

liability of the United States for infringement by acts that 

are performed with its authorization and consent. 28 

U.S.C. § 1498(a) (“Whenever an invention described in 

and covered by a patent of the United States is used or 

manufactured by or for the United States without license 

of the owner thereof or lawful right to use or manufacture 

the same, the owner’s remedy shall be by action against 

the United States in the United States Court of Federal 

Claims for the recovery of his reasonable and entire 

compensation for such use and manufacture.”). By statute the contractor is immunized from liability. Id. (“use 

or manufacture ... by a contractor ... shall be construed as 

use or manufacture for the United States”). This court 

dismissed Lockheed as a party, negated the proposed 

transfer to Georgia, and remanded to the Court of Federal 

Claims for inclusion of counts for infringement with 

respect to both the F-22 Fighter and the B-2 Bomber. 

Zoltek Corporation v. United States, 672 F.3d 1309, 1311

(Fed. Cir. 2012) (en banc) (Zoltek II).

On remand, the CFC separated trial of the issues of 

validity and infringement, and denied discovery as to 

infringement with respect to the F-22 Fighter. Zoltek 

sought mandamus from this court concerning these 

actions; the petition was denied. In re Zoltek Corporation,

526 F. App’x 956, 957 (Fed. Cir. 2013) (non-precedential). 

Trial proceeded in the CFC, limited to validity. The 

government challenged the ’162 patent under sections 

101, 103, and 112 of Title 35. The CFC sustained patent 

eligibility under section 101; that ruling is not appealed. 

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At trial, each side presented an expert witness, Dr. 

Brian Sullivan for the government and Mr. Zsolt Rumy

for Zoltek. The CFC held the asserted claims invalid on 

the grounds of obviousness and inadequate written description. Zoltek Corporation v. United States, No. 96-166 

C, 2014 WL 1279152 (Fed. Cl. Mar. 31, 2014) (“CFC Op.”). 

Zoltek appeals, arguing that the CFC applied incorrect 

laws of written description and obviousness, that the CFC

did not apply the appropriate burdens and standards of 

proof, and that the CFC erred in its conclusions. 

Zoltek also argues that the issues were improperly bifurcated. We conclude that in the circumstances of this 

case, taking note of the government’s official invocation of 

state secret privilege, the CFC acted within its discretion 

in limiting trial initially to the issues of validity. However, as we next discuss, we conclude that the trial court 

erred in its judgment of patent invalidity. 

The Boyd Invention

The ’162 patent is directed to a method of manufacturing carbon fiber sheet products whose electrical resistivity is pre-selected and value-controlled by the described 

method. This method is based on Boyd’s discovery of a 

non-linear relationship among the heat treatment conditions, partial carbonization, and surface resistivity1 of 

sheet products. 

The method as claimed in the reissue patent starts 

with a previously oxidized and stabilized carbonizable 

fiber, a product known in the prior art and commercially 

available. This oxidized fiber is then partially carbonized 

 

1 Throughout these proceedings, the terms resistivity and resistance were often used interchangeably. The 

correctness of these usages is not at issue.

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in accordance with the relationship discovered by Boyd, to 

produce a partially carbonized fiber whose sheet products 

have the desired pre-selected surface electrical resistance.

This method permits production of carbonized sheets 

of pre-selected and uniform electrical resistance, and thus 

uniform pre-selected insulating properties. The ’162 

specification states that theretofore carbon fiber sheets 

having specified surface electrical resistance were available only by including other materials, such as glass or 

aluminum filaments, with the carbonized fibers. ’162 

patent, col.1 ll.49–60.

Patent Figure 4 shows the foundation discovery of resistivity as a function of carbonizing temperature:

The lower curve represents the volume resistivity for 

single fibers at the carbonizing temperature, and upper 

curves A and B show surface resistivities for one half 

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 6 ZOLTEK CORP. v. US

ounce per square yard and one ounce per square yard 

sheet products incorporating the designated partially 

carbonized fibers. The patent describes and exemplifies 

the preparation of fibers having the preselected partial 

carbonization, and the production of sheet products having the desired electrical properties. Id., col.4 ll.19–23 

(“[T]he temperature-resistivity of the single carbonized 

fiber is translated into the preselected desired surface 

resistance of the resultant partially carbonized fiber sheet 

product produced with such fibers.”).

It is not disputed that the non-linear relationship

shown in Figure 4, and its application to achieve the 

results described in the ’162 patent, were not previously 

known. The government’s expert, Dr. Sullivan, stated to 

be one of the nation’s preeminent experts with a “thirtyyear career in research and design relating to carbon fiber 

science,” U.S. Br. 22, testified that his calculations pertaining to his reproduction of the Figure 4 curve were 

based on data that were not in the prior art and were 

selected retrospectively. No reference showed the relationship between volume or surface-resistivity of carbon 

fiber sheet products and treatment temperature of carbon 

fibers.

The CFC held claims 1–22 and 33–38 of the reissue 

patent invalid on two grounds, (1) that they did not meet 

the written description requirement, and (2) that the 

claimed invention would have been obvious to a person of 

ordinary skill in this field at the time of the invention.

I 

Written Description

The claimed method is summarized in reissue claim 1, 

shown as in the reissue patent, with deletions from the 

original claim in brackets and additions in italics—for 

these changes are the basis of the CFC’s ruling of invalidity on the ground of inadequate written description:

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ZOLTEK CORP. v. US 7

1. A method of manufacturing a plurality of different value controlled resistivity carbon fiber 

sheet products employing a carbonizable fiber 

starting material; said method comprising [oxidizing and stabilizing the carbonizable fiber starting 

material at an elevated temperature of the order 

of 220 degrees Centigrade to effect molecular aromatic rearrangement of the fibers,] selectively 

partially carbonizing [the] previously oxidized and 

stabilized fiber starting material for a predetermined period in an oxygen free atmosphere within 

a furnace at [a] selected temperature values within a temperature range from 370 degrees Centigrade to about 1300 degrees Centigrade by 

soaking the stabilized fiber starting material at 

the selected temperature for the predetermined 

period of time to provide a [desired] preselected 

known volume electrical resistivity to the partially

carbonized fibers corresponding to that volume 

electrical resistivity value required to provide the 

preselected desired surface resistance value for the 

finished sheet products, and thereafter processing 

the partially carbonized fibers into [desired electrical resistivity] homogeneous carbon fiber sheet 

products [having the form of non-woven paper or 

woven or knitted fabric sheet products] having the

preselected desired surface electrical [resistivities] resistances. 

The CFC held that the original patent did “not support the elimination of the oxidation and stabilization 

step” from the reissued claims, and that this rendered the 

claims “invalid for lack of written description.” CFC Op. 

at *20-21. The CFC explained that the reissue “impermissibly broadens the patented process by reducing the 

number of steps required for infringement.” Id. at *21. 

The CFC stated that “although the step is found in the 

reissue patent, its elimination from the claimed process 

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goes beyond the written description of the invention in the 

original ’395 patent.” Id. at n.10 (emphasis in original). 

The elimination of the preparation of the starting material broadened the reissue. However, a broadening 

reissue is not improper if filed within two years of issuance. A patentee is entitled to a reissue “enlarging the 

scope of the claims,” when, as here, the reissue application is filed “within two years from the grant of the original patent.” 35 U.S.C. § 251(d).

The CFC also held that the broadened claim is not 

supported in the specification, holding that it is irrelevant 

that the omitted oxidizing and stabilizing step is fully 

described in the specification as well as being in the prior 

art. The CFC held that the preparation of the known 

starting material must be included in the claim, that it is 

insufficient that the reissue claim requires that these 

steps be performed, and that whether these steps were 

known to the prior art is “irrelevant to the question of 

whether the written description requirement is satisfied.” 

CFC Op. at *19. 

There was no argument as to insufficiency of either 

the prior art or the content of the specification, in describing the starting material. There was no allegation that a 

person of ordinary skill in this field would not understand 

the description in the specification. The original specification plainly, and without dispute, describes that the 

starting material is an oxidized and stabilized fiber, cites 

references showing this known material, and describes its 

preparation. That a previously oxidized and stabilized 

starting material was known to a person of ordinary skill 

in the field was recognized by the reissue Examiner in his 

statement that:

Ex[amine]r agreed with applicant that partial oxidation & heat stabilization temp. need not be recited in the claims since this temp. is within the 

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ZOLTEK CORP. v. US 9

prior art & claims do not have to recite what is 

well known in the prior art.

Examiner Interview Summary, Reissue Application No. 

07/483,531 (May 5, 1992). 

The CFC had previously construed the reissue claims 

as supported by the specification, finding that the reissue 

claims were substantially the same as in the parent 

patent and properly supported. The court stated:

[I]t can hardly be said that the oxidizing and stabilizing step was removed from Reissue ’162. On 

the contrary, when the step was removed the examiner rejected the application until Zoltek added 

“previously” in the claims to refer back to this description of the method which requires it unless a 

previously oxidized and stabilized material is purchased.

Opinion on Defendant’s Motion for Partial Summary 

Judgment on Matters Relating to Reissue filed on January 15, 1999, No. 96-166 C (Fed. Cl. Sept. 13, 1999) (unpublished). 

The government argues that the asserted claims are 

not supported in the specification because the specification does not state that these steps need not be performed 

by the same entity. The question of who performs steps of 

a fully described invention, including preparation of a 

known starting material, is not a matter of the written 

description requirement.

The purpose of the written description requirement is 

to assure that the public receives sufficient knowledge of 

the patented technology, and to demonstrate that the 

patentee is in possession of the invention claimed. See In 

re Skvorecz, 580 F.3d 1262, 1269 (Fed. Cir. 2009). The 

requirement is applied in the context of the state of 

knowledge at the time of the invention. Capon v. Eshhar, 

418 F.3d 1349, 1358 (Fed. Cir. 2005). The written deCase: 14-5082 Document: 50-2 Page: 9 Filed: 02/19/2016
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scription “need not include information that is already 

known and available to the experienced public.” Space 

Sys./Loral, Inc. v. Lockheed Martin Corp., 405 F.3d 985, 

987 (Fed. Cir. 2005); see Enzo Biochem, Inc. v. Gen-Probe 

Inc., 323 F.3d 956, 970 (Fed. Cir. 2002) (“[The written] 

description is the quid pro quo of the patent system; the 

public must receive meaningful disclosure in exchange for 

being excluded from practicing the invention for a limited 

period of time.”). 

Here, the ’162 specification describes the preparation 

of the starting material, and states that it is commercially 

available. ’162 patent, col.4 ll.45-55 (“[T]he carbonizable 

tow is supplied to an oxidation operation 14 where it is 

stabilized by being heated in atmospheric oxygen to a 

temperature of about 220 degrees Centigrade . . . . The 

resulting oxidized tow is sold under the trademark 

‘PYRON.’”). The government does not argue that a person 

of ordinary skill would not be able to make or acquire the 

starting material based on the description in the specification.

The written description requirement relates to 

whether the patentee possessed the invention that is 

claimed. There was no suggestion that a person of ordinary skill would not have understood that Boyd was in 

possession of the invention that he claimed. See Centocor 

Ortho Biotech, Inc. v. Abbott Labs., 636 F.3d 1341, 1348 

(Fed. Cir. 2011) (“To satisfy the written description requirement, the applicant must convey with reasonable 

clarity to those skilled in the art that, as of the filing date 

sought, he or she was in possession of the invention, and 

demonstrate that by disclosure in the specification of the 

patent.”) (internal quotation marks omitted); see also 

Alcon Research Ltd. v. Barr Labs., Inc., 745 F.3d 1180, 

1191–92 (Fed. Cir. 2014) (“Critically, Barr adduced no 

evidence, let alone clear and convincing evidence, that 

was probative of whether an ordinarily skilled artisan 

would not have understood from the disclosures of AlCase: 14-5082 Document: 50-2 Page: 10 Filed: 02/19/2016
ZOLTEK CORP. v. US 11

con’s . . . patents that the patentees invented, or possessed, the methods of the asserted claims. Without that 

evidence, there was no basis on which to find a lack of 

adequate written description.”).

The CFC stated its concern that the reissue patent 

claims could be infringed by an entity that did not itself 

make the starting material, but purchased the known 

starting material from a commercial source. However, 

the reissue statute provides that reissue is available “by 

reason of the patentee claiming more or less than he had 

a right to claim . . . for the invention disclosed in the 

original patent.” 35 U.S.C. § 251(a). A validly obtained 

reissue does not violate the written description requirement if the patentee can reach an enlarged scope of 

possible infringement.

It is not an improper broadening amendment when a 

reissue applicant, with the considered agreement of the 

reissue Examiner, substitutes a preparatory step known 

to those skilled in the art at the time of the invention with 

a requirement to start with the product of that known

preparatory step. The CFC’s emphasis on who might 

infringe the broadened reissue claims is an issue of infringement, not written description.

We conclude that the CFC erred in holding reissue 

claims 1–22 and 33–38 invalid for failure to meet the 

written description requirement of section 112. That 

ruling is reversed.

II

Obviousness 

The science of carbonized fiber materials had been the 

subject of study well before the Boyd patent application 

was filed, as exemplified in the references cited during 

patent prosecution and in these proceedings.

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The CFC relied on the government’s expert Dr. Sullivan, who cited references concerning carbon fiber products and developed a mathematical formula from which 

he generated a graph duplicating that in Figure 4 of the 

’162 patent. To produce this graph, Dr. Sullivan used 

data from the ’162 patent record, from a Zoltek publication issued in 2000, and various references and articles. 

He cited: 

[1] Akio Shindo, Studies on Graphite Fiber, Government Industrial Research Institute of Osaka (1961), is a

research report discusses the manufacture and use of 

carbon fibers of polyacrylonitrile. Shindo states that 

increasing heat-treatment temperature of the fiber results 

in increased conductivity of the fiber. Shindo does not 

show or suggest the non-linear relationship between 

temperature and resistivity that was discovered by Boyd, 

or the use of such relationship to control surface resistivity.

[2] Kitago, U.S. Patent No. 3,998,689 (Dec. 21, 1976), 

describes the production of carbon fiber sheets by a process that combines chopped carbon fibers with other 

ingredients to form a slurry, which is shaped into a sheet, 

saturated with a resin, and then carbonized, to form a 

conductive sheet product. Kitago provides data for sheets 

carbonized at 1000°C and 2000°C, showing significantly 

lower resistivity at the higher temperature. Kitago does 

not show or suggest the non-linear relationship discovered 

by Boyd, or the use of such relationship to control surface 

resistivity.

[3] Layden, U.S. Patent No. 4,080,413 (Mar. 21, 1978), 

shows carbonization of chopped polyacrylonitrile fiber 

sheets over the range of 1000°C to 1260°C, to produce 

hard, inflexible products with extremely low surface 

resistivities, suitable for use as fuel cell electrodes. Leyden does not show or suggest the non-linear relationship 

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ZOLTEK CORP. v. US 13

discovered by Boyd, or the use of such relationship to 

control surface resistivity.

[4] Topchjiev, U.K. Patent No. 979,122 (Jan. 1, 1965), 

entitled “Method of Producing Semiconductive Polymer 

Materials,” uses oxidized and stabilized carbon fibers that 

are heat treated to produce materials with semiconductor 

properties electrical conductivity. Topchjiev does not 

show or suggest the non-linear relationship discovered by 

Boyd, or the use of such relationship to control surface 

resistivity.

[5] D.B. Fischbach & Kunio Komaki, Electrical Resistance of Carbon Fibers, University of Washington 

(1979), is an article that explains that increasing the 

treatment temperature results in decreased volume 

resistivity. This article does not show or suggest the nonlinear relationship discovered by Boyd, or the use of such 

relationship to control surface resistivity.

These references variously show the heat treatment of 

carbonized fibers and their resistivities or conductivities 

at various treatment temperatures. On crossexamination, Dr. Sullivan agreed that these references 

alone do not establish obviousness. The following exchange took place:

Q. And the Fischbach and Komaki article . . . the 

Topchjiev patent . . . the Layden patent . . . all 

disclose nothing more than what was disclosed in 

the Otani reference before the Patent Office, correct?

A. I believe that is correct, yes.

Q. And I believe it’s also your testimony — prior 

testimony that the Topchjiev patent and the Layden patent, by themselves, would not be sufficient 

to render the Zoltek patent obvious, correct?

A. Yes, I think that is correct.

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Trial Tr. 269:5–15.

Instead, Dr. Sullivan relied on a mathematical formula he derived from the Rule of Mixtures,2 citing several 

articles, viz., “Theory of Reinforced Materials” by Z. 

Hashin (1972), “Analysis of Composite Materials—A 

Survey” by Z. Hashin (1981), “An Analysis Model for 

Spatially Oriented Fiber Composites” by B.W. Rosen et al. 

(1977), and “Mechanics of Composite Materials” by R. 

Christensen (1979). The position of Dr. Sullivan was 

summarized at trial as follows: 

Q.: So, to sum up your testimony, Dr. Sullivan, 

you’re asserting that it would be obvious to a person of ordinary skill in the art, as of October 1984, 

to rely upon four publications which do not mention surface resistivity, partially carbonized or 

semi-conductive carbon fibers, or the method to 

control the surface resistivity of carbon fiber sheet 

products made from the — made from the partially carbonized fibers and controlling the volume resistivity of the partially carbonized fiber, the 1972 

Hashin and the 1977 Rosen articles referring to 

structural fibers, that it would have been obvious 

to a person of ordinary skill in the art, as of October of 1984, to construct the mathematical methodology you described on your direct examination 

 

2 The Rule of Mixtures is a rule of materials science 

in which a weighted mean is used to predict properties, 

including electrical conductivity, of a composite material 

made up of continuous and unidirectional fibers. It is a 

mathematical equation by which properties of the individual components of a mixture are weighted by their 

volume fractions.

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to obtain carbon fiber sheet products having a 

controlled surface resistivity?

[Objection] 

THE COURT: . . . . do you want the question broken out or — 

THE WITNESS: No, because that is my testimony.

Trial Tr. 245:12–246:8. 

No reference mentions “surface resistivity” or “the required limitation to pre-select individual fiber volume 

resistivities to produce sheet products with desired surface resistivities.” Zoltek Br. 4–5 (citing record). Dr. 

Sullivan testified that he was not aware of anyone, including himself, who had previously used the mathematical 

formula he created to determine carbonization temperature-resistivity relationships.

The ’162 patent teaches carbonized sheets that “require no insulating elements such as glass fiber in order 

to adjust the surface resistances of the sheet product to a 

desired surface resistance volume.” ’162 patent, col.2 ll.7–

11. The novelty of such sheets was not disputed. The 

patent prosecution and trial records contain a letter from

George Rodgers, a materials engineer at Northrup 

Grumman (the general contractor for the B-2 Bomber), 

who stated:

In December 1983, the Material & Processes Department of Northrop Advanced Systems Division 

ordered four rolls of carbon fiber paper from 

Stackpole Fibers Co. The product was unique in 

that the carbon fibers were not fully carbonized, 

increasing the volume resistivity of the fiber 

which in turn increases the surface resistivity of 

the paper. . . . At the time the order was placed, 

Northrop Materials & Processes had never seen a 

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 16 ZOLTEK CORP. v. US

material of this type before and was not aware of 

any other company that could supply material in 

this form with varying electrical properties.

Letter from George Rodgers dated August 6, 1987, Prosecution File Wrapper 187. By deposition on August 18, 

2009, Mr. Rodgers testified that, with regard to the accuracy of the contents of that letter, viewed in hindsight, “I 

wouldn’t change anything.” Rogers Dep. 34:6.

Dr. Sullivan also testified that he had no basis to disagree with the Rodgers letter. Specifically, he testified:

Q. Okay. And the last sentence reads, “At the time 

the order was placed, Northrop Materials & Processes had never seen a material of this type and 

were not aware of any other company that could 

supply material in this form with varying electrical properties.” Do you see that?

A. I do.

Q. Okay. And you have no basis to disagree with 

that statement, do you?

A. No, I don’t.

Trial Tr. 274:16–25.

There is no teaching or suggestion in the prior art to 

select the data that Sullivan selected, and to plug the 

selected data into the mathematical equation that Sullivan devised. As summarized by Zoltek, “Sullivan used 

the variable fiber volume resistivities shown [in] the file 

history of the ’395 parent patent at various temperatures 

and constant volume resistivities for each remaining 

component of the sheet products in making his calculations.” Zoltek Br. 23 (citing record). This is not evidence 

of obviousness. See EWP Corp. v. Reliance Universal, 

Inc., 755 F.2d 898, 907 (Fed. Cir. 1985) (“Patentability 

under the statute, § 103, is a decision made on the basis of 

a hypothesis: Would the invention have been obvious ‘to a 

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person having ordinary skill in the art to which the subject matter pertains’ in the light of all knowledge conveyed by ‘prior art’ as defined by statute and case law.”). 

Zoltek also points to several errors made by Dr. Sullivan, to which Sullivan admitted on cross-examination. 

Zoltek mentions “Sullivan’s erroneous fiber volume fraction (0.3), fiber density (1.81 g/cm3), and resin volume 

fraction (0.54).” Zoltek Br. 24 n.5. With respect to Dr. 

Sullivan’s testimony that he used a volume fraction of 0.3 

in his Rule of Mixtures calculation purportedly reflective 

of the Zoltek patented product, Zoltek’s expert Mr. Rumy 

testified: 

In the paper process, you can’t even make that 

kind of conduct — that kind of concentration of 

carbon fibers, only possibly by taking a regular 

paper product that is made probably no more than 

10 to 15 percent carbon content, and then you 

compress it. But we — that’s — that would be destroying our entire invention.

Trial Tr. 326:22–327:2. 

As another error, while the Rule of Mixtures requires

the use of volume fractions of each component of a composite mixture, Dr. Sullivan used a weight percent for each 

component in order to place data points on the Figure 4 

template. See Zoltek Br. 28.

These errors taint Dr. Sullivan’s reproduction of Figure 4. Indeed, Dr. Sullivan made several confessions of 

error in his selection or calculation of data points to 

produce the graph he created to track Figure 4. As another example:

Q. . . . So, you’ve inserted a uniform density of 

1.81 grams per cubic centimeter, which is the density of fully carbonized fibers, when there should 

have been a gradually increasing density from 

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 18 ZOLTEK CORP. v. US

1.36 through the temperature range shown on 

[your spreadsheet], correct?

[Objection for lack of foundation; overruled] 

A. It is true that the carbon fiber density will 

change with heat treatment temperature and that 

it probably is true that a different value, other 

than a uniform 1.81, would have been more appropriate 

Q. Okay. 

A. I will concede that.

Trial Tr. 257:2–19. 

Zoltek also points to Dr. Sullivan’s admission that his 

critical fiber volume fraction, 0.3%/30%, fundamental to 

his calculations based on the Rule of Mixtures, was wrong 

and that Dr. Sullivan used data from a 2000 Zoltek User’s 

Guide directed to fully carbonized composites at a temperature of 1400°C, a reference published fourteen years 

after the ’162 patent’s filing date.

Dr. Sullivan conceded that there were errors in his 

calculations, stating that the reason was that he did not 

have complete information. That is not surprising, for 

there was not complete information in the prior art— 

weighing against the government’s argument that it 

would have been obvious to a person of ordinary skill to 

recreate the Boyd graph from known information. Dr. 

Sullivan’s plaint that he could not accurately duplicate 

Boyd’s discovery because of lack of information is powerful evidence of non-obviousness—not the contrary.

Dr. Sullivan stated that he obtained some of the values he used in his calculations from the ’162 patent itself. 

However, for the volume fraction of carbon fiber, described by Dr. Sullivan as by far the most important 

element in the equation, he ignored the figure in the 

patent (0.83) and used a value of 0.3, which he testified 

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came from a Zoltek 2000 User’s Guide. Zoltek points out 

that this Guide was directed to an entirely different 

product, and also that the Guide was written fourteen 

years after the ’162 patent application was filed. There 

was no showing that the information on which Dr. Sullivan relied was available to persons of skill at the time of 

the Boyd invention. Zoltek states, and Dr. Sullivan did 

not contradict, that Dr. Sullivan selected values from 

various sources in order to fit the template of Boyd’s 

results.

Neither the government’s attorney argument, nor Dr. 

Sullivan’s testimony, nor the opinion of the Court of 

Federal Claims, points to any suggestion in the prior art 

to select the data selected by Dr. Sullivan and create the 

mathematical formula to construct a graph to track 

Figure 4. See KSR Int’l Co. v. Teleflex, Inc., 550 U.S. 398, 

418–19 (2007) (“Although common sense directs one to 

look with care at a patent application that claims as 

innovation the combination of two known devices according to their established functions, it can be important to 

identify a reason that would have prompted a person of 

ordinary skill in the relevant field to combine the elements in the way the claimed new invention does. This is 

so because inventions in most, if not all, instances rely 

upon building blocks long since uncovered, and claimed 

discoveries almost of necessity will be combinations of 

what, in some sense, is already known.”).

Even Dr. Sullivan called his reconstruction of Figure 

4 “somewhat arbitrary.” Trial Tr. 259:18. Hindsight 

reconstruction for litigation ends is not of probative value. 

See Outside the Box Innovations, LLC v. Travel Caddy, 

Inc., 695 F.3d 1285, 1298 (Fed. Cir. 2012) (“Precedent 

recognizes the pitfalls of judicial hindsight exercised at 

the time of litigation . . . .”).

The Court has recognized “the distortion caused by 

hindsight bias” and “arguments reliant upon ex post

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 20 ZOLTEK CORP. v. US

reasoning” in determining obviousness. KSR, 550 U.S. at

421; see InTouch Technologies, Inc. v. VGO Commc’ns, 

Inc., 751 F.3d 1327, 1351 (Fed. Cir. 2014) (“It appears 

that [the expert] relied on the . . . patent itself as her 

roadmap for putting what she referred to as pieces of a 

‘jigsaw puzzle’ together.”); W.L. Gore & Associates, Inc. v. 

Garlock, Inc., 721 F.2d 1540, 1553 (Fed. Cir. 1983) (“To 

imbue one of ordinary skill in the art with knowledge of 

the invention in suit, when no prior art reference or 

references of record convey or suggest that knowledge, is 

to fall victim to the insidious effect of a hindsight syndrome wherein that which only the inventor taught is 

used against its teacher.”).

The government does not attempt to rehabilitate Dr. 

Sullivan’s errors. Instead, the government’s argument 

appears to be that since Dr. Sullivan is a renowned scientist in this field, and since Dr. Sullivan was able to reproduce the Figure 4 graph, it was obvious to do so. This was 

error, since, as we have repeatedly cautioned, “[t]hat 

which may be made clear and thus ‘obvious’ to a court, 

with the invention fully diagrammed and aided . . . by 

experts in the field, may have been a break-through of 

substantial dimension when first unveiled.” Uniroyal, 

Inc. v. Rudkin-Wiley Corp., 837 F.2d 1044, 1051 (Fed. Cir. 

1988) (internal quotation marks omitted); see also KSR, 

550 U.S. at 421 (“A factfinder should be aware, of course, 

of the distortion caused by hindsight bias and must be 

cautious of arguments reliant upon ex post reasoning”) 

(citing Graham v. John Deere Co., 383 U.S. 1, 36 (1966) as

“warning against a temptation to read into the prior art 

the teachings of the invention in issue and instructing 

courts to guard against slipping into use of hindsight”) 

(internal quotation marks omitted); W.L. Gore, 721 F.2d 

at 1553 (“It is difficult but necessary that the decisionmaker forget what he or she has been taught at trial 

about the claimed invention and cast the mind back to the 

time the invention was made (often as here many years), 

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ZOLTEK CORP. v. US 21

to occupy the mind of one skilled in the art who is presented only with the references, and who is normally

guided by the then-accepted wisdom in the art.”). 

There was not clear and convincing evidence of obviousness of the Boyd discovery and its use to produce 

carbon fiber sheets of pre-selected homogeneous electrical 

resistance. The CFC’s ruling of invalidity on the ground 

of obviousness is reversed.

CONCLUSION

The Court of Federal Claims erred in holding the asserted claims of the ’162 patent invalid under sections 103 

and 112. The judgment of invalidity is reversed. We 

remand for resolution of all remaining issues. 

REVERSED AND REMANDED

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