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Nature of Suit Code: 830
Nature of Suit: Patent
Cause of Action: 

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United States Court of Appeals 

for the Federal Circuit ______________________ 

SONIX TECHNOLOGY CO., LTD.,

Plaintiff-Appellant

v.

PUBLICATIONS INTERNATIONAL, LTD., SD-X 

INTERACTIVE, INC., ENCYCLOPEDIA 

BRITTANNICA, INC., HERFF JONES, INC.,

Defendants-Appellees

______________________ 

2016-1449

______________________ 

Appeal from the United States District Court for the 

Northern District of Illinois in No. 1:13-cv-02082, Judge 

Amy J. St. Eve.

______________________ 

Decided: January 5, 2017

______________________ 

JONATHAN HANGARTNER, X-Patents, APC, La Jolla, 

CA, argued for plaintiff-appellant. Also represented by 

STEVEN P. FALLON, Greer, Burns & Crain, Ltd., Chicago, 

IL.

JACOB DANIEL KOERING, Miller, Canfield, Paddock, & 

Stone, PLC, Chicago, IL, argued for defendants-appellees. 

Also represented by TERRENCE JOSEPH SHEAHAN, Freeborn & Peters, LLP, Chicago, IL. 

______________________ 

Case: 16-1449 Document: 62-2 Page: 1 Filed: 01/05/2017
2 SONIX TECH. CO. v. PUBL’NS INT’L, LTD. 

Before LOURIE, O’MALLEY, and TARANTO, Circuit 

Judges.

LOURIE, Circuit Judge. 

Sonix Technology Co., Ltd. (“Sonix”) appeals from the 

district court’s grant of summary judgment following its

determination that claims 9, 25, 35–36, 52–55, 57–60, 62–

64, 66, 68, 71–77, 79–82, and 85–90 (“the asserted 

claims”) of Sonix’s U.S. Patent 7,328,845 (“the ’845 patent”) are invalid as indefinite. See Sonix Tech. Co. v. 

Publ’ns. Int’l, Ltd., No. 13-cv-2082, 2015 WL 8153600, at 

*9–17 (N.D. Ill. Dec. 8. 2015) (“Opinion”). Specifically, the 

district court concluded that the term “visually negligible” 

rendered the asserted claims indefinite under 35 U.S.C. 

§ 112 ¶ 2.1 For the reasons that follow, we reverse the 

determination of indefiniteness and hence the summary 

judgment of invalidity. 

BACKGROUND

Sonix owns the ’845 patent, which describes a system 

and method for using a “graphical indicator” (e.g., a 

matrix of small dots) to encode information on the surface 

of an object. See ’845 patent, col. 3 ll. 6–43. The surface

may feature additional information as well; for example, 

illustrations or icons in a children’s book. Id. col. 7 ll. 1–6. 

The invention also includes an “optical device” that can 

read the graphical indicator and output further information. Id. col. 7 ll. 18–32. Figure 5 illustrates an 

example: 

1 Because the ’845 patent was filed before the enactment of the Leahy-Smith America Invents Act, Pub. L. 

No. 112-29, § 3, 125 Stat. 284, 285–93 (2011), the prior 

version of § 112 governs. See Fleming v. Escort, Inc., 774 

F.3d 1371, 1374 n.1 (Fed. Cir. 2014). 

 

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Id. fig.5. In this example, an icon showing a person riding 

a horse (511) is printed on the page of a book (51). Id. col. 

7 ll. 1–10. The graphical indicator (512) is printed in the 

same area as the icon. Id. col. 7 ll. 18–21. The optical 

device (311) captures an image that includes the graphical indicator. Id. col. 7 ll. 21–24. The processing device 

(312) retrieves the indicator from the image and outputs 

additional information. Id. In this particular example, 

holding the optical device over the horse icon could cause 

the device to output “audio information, such as pronunciations of horse in English.” Id. col. 7 ll. 27–32. 

Of course, encoding information on the surface of an 

object is not new. The ’845 patent admits that information has been recorded on the surface of objects 

“[d]ating back to ancient time[s],” id. col. 1 ll. 15–16, and

lists a bar code as a “conventional” example of a graphical 

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indicator, id. col. 9 ll. 46–57. The ’845 patent purports to 

improve on conventional methods by rendering the graphical indicator “visually negligible.” Id. col. 3 ll. 5–11. The 

patent uses a book cover to illustrate the difference between a conventional bar code and the claimed indicator: 

Id. figs.12(A) & 12(B). The graphical indicator (10002) in 

figure 12(B) stores the same information as the bar code

(10001) in figure 12(A), but in a manner that does not 

“interfere with the other main information on the surface.” Id. col. 9 ll. 47–57. 

The “[e]xemplary [d]esign,” id. col. 3 l. 5, of the 

claimed indicator “includes multiple graphical micro-units 

arranged in a layout.” Id. col. 3 ll. 14–15. In one embodiment the micro-units are dots, arranged in a matrix. Id.

col. 3 ll. 15–25. Each cell in the matrix either contains or 

does not contain a dot, resulting in a unique pattern that 

can store information. Id. col. 3 ll. 38–30, col. 4 ll. 13–41. 

The written description also discloses differentiability, 

brightness, and homogeneity “requirements for the graphical indicators being negligible to human eyes.” Id. col. 4 

ll. 60–61. First, the indicator must be so small that 

“human eyes cannot differentiate one graphical indicator 

from others.” Id. col. 4 ll. 61–63. The patent indicates 

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that “[f]or best result, the graphical micro-unit must be so 

tiny that only a microscope apparatus can detect it.” Id.

col. 3 ll. 24–25. Second, the patent advises that the 

number of micro-units should be reduced based on “the 

size of the graphical micro-unit, the pitch between microunit, and the desired visual effect,” so that they “have 

little influence on the brightness of the surface of the 

object.” Id. col. 4 l. 67–col. 5 l. 1. Finally, the “number of 

graphical micro-units of each graphical indicator” should 

be “substantially equal to each other,” so that “the graphical indicators look more homogenous to human eyes and 

become invisible to human eyes.” Id. col. 5 ll. 1–5. 

The written description also gives two examples of 

visually-negligible indicators. In the first, each square 

centimeter contains 3,000 matrix cells, of which less than 

70% contain graphical micro-units, and where each microunit occupies less than 80% of the cell. Id. col. 5 ll. 6–10. 

The second is similar, but requires each square centimeter to include 6,000 cells. Id. col. 5 ll. 11–15. 

In 2010, Sonix alleged that children’s books using dot 

pattern technology produced by GeneralPlus, a Taiwanese 

company, infringed the ’845 patent. In response, SunPlus 

Technology Co. Ltd. (“SunPlus”), GeneralPlus’s parent 

company, requested ex parte reexamination of the ’845 

patent (“the first reexamination”) by the U.S. Patent and

Trademark Office (“USPTO”). On December 27, 2011, the 

USPTO confirmed the patentability of, inter alia, asserted 

claims 9, 25, and 35–36, and allowed new, and now asserted, claims 52–55, 57–60, 62–64, 66, 68, 71–77, 79–82, 

and 85–90, among others. J.A. 94–96.

Less than one month later, GeneralPlus requested 

another ex parte reexamination (“the second reexamination”). J.A. 1937. One of the central disputed issues

during this second reexamination was whether the combination of U.S. Patent 5,416,312 (“Lamoure”) and U.S. 

Patent 5,329,107 (“Priddy”) would have led to a visuallyCase: 16-1449 Document: 62-2 Page: 5 Filed: 01/05/2017
6 SONIX TECH. CO. v. PUBL’NS INT’L, LTD. 

negligible indicator, as the examiner initially rejected all 

pending claims over that combination. See, e.g., J.A. 

2328–31. Sonix responded to that rejection with a declaration from Serjer Serjersen (“Serjersen”), an expert with 

more than thirty years of experience. J.A. 2337. Serjersen declared that he created graphical indicators using 

the processes described by the ’845 patent and by the 

cited references, and determined that only the indicator

produced using the process of the ’845 patent was visually 

negligible. J.A. 2338–44, 5313–25. The examiner confirmed the patentability of the asserted claims on the 

basis of Serjersen’s declaration, specifically indicating 

that the combination of cited references did not disclose a 

visually-negligible graphical indicator. J.A. 2362–65. 

In 2013, Sonix alleged that Publications International, Ltd., SD-X Interactive, Inc., Encyclopedia Brittannica, 

Inc., and Herff Jones, Inc. (collectively, “Appellees”) 

infringed the asserted claims. Appellees’ initial invalidity

contentions identified twenty-six claim limitations that 

they believed to be indefinite; however, that list did not 

include the term “visually negligible.” See J.A. 2637–41. 

In their final invalidity contentions, Appellees contended 

that two additional claim limitations were indefinite, but 

again did not question “visually negligible.” J.A. 3031.

During claim construction, Appellees initially asked 

the district court to construe “visually negligible,” J.A. 

2430, but, when they retained new counsel, proposed that 

the term be given its ordinary meaning, J.A. 2434–36. 

Sonix agreed with an ordinary-meaning construction, and 

so the district court did not construe “visually negligible.” 

Even so, “visually negligible” was used repeatedly in 

the expert reports. For example, Sonix’s expert, 

Dr. Ashok, opined that the accused products included 

visually-negligible indicators, J.A. 3087–88, and that the 

cited prior art did not, J.A. 3539–41, 3547. Appellees’ 

expert, Dr. Engels, also applied “visually negligible” 

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throughout his reports, and even agreed that “the dot 

patterns in the specific products reviewed by Dr. Ashok in 

his Report are visually negligible . . . .” J.A. 4210–11. On 

validity, Dr. Engels repeatedly opined that the indicators 

disclosed in Lamoure and Priddy—the same references at 

issue in the second reexamination—were visually negligible. See J.A. 5348–49, 5355–56, 5418, 5430–31. But Dr. 

Engels did not opine that “visually negligible” was indefinite. See id. Elsewhere in his report, Dr. Engels contended that alternatives to the claimed invention would have 

been available because “it would be a simple matter to 

ensure that any pattern being used would be printed in a 

manner that would be visually negligible compared to the 

main information on a page.” J.A. 4228. 

At Dr. Ashok’s deposition, after the close of fact discovery and after the parties agreed to an ordinary meaning for “visually negligible,” he was asked to explain 

“what does [‘visually negligible’] mean to you?” J.A. 4755

at 46:25–47:1. Dr. Ashok indicated that he understood it 

“to mean that if these dot patterns are imprinted on a 

surface, with a cursory look, I will not notice that.” Id. at 

47:2–7. Dr. Ashok was then asked whether there was 

“any sort of objective standard” for visual negligibility. 

J.A. 4756 at 49:11. Dr. Ashok explained that visibility 

depended on the ink used, the printing pattern, and the 

size of the dot, but that there “is not a universal standard

by any means because it depends on the visual acuity of 

the observer.” Id. at 50:24–51:4. Even so, Dr. Ashok 

indicated that his “method of determining visual negligibility would be [to] print at the magnification desired and 

look at it,” because he “would imagine that would be 

representative of most people looking at it.” Id. at 51:5–8. 

In response, Dr. Engels asserted at his deposition that 

“visually negligible” was subjective because “there is no 

objective test to define the boundary between visually 

negligible and visually non-negligible.” Dr. Engels did not

analyze the intrinsic evidence, and did not provide any 

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detail explaining his conclusion. J.A. 3709. On the basis 

of the two expert depositions, Appellees amended their 

invalidity contentions and moved for summary judgment 

of indefiniteness. 

The district court ultimately held that the claims are 

invalid as indefinite. Opinion, 2015 WL 8153600, at *9–

17. Reasoning that “visually negligible” is “purely subjective” and that the claim language does not provide guidance on its meaning, the court turned to the other 

intrinsic evidence. Id. at *13. The court determined that 

the written description does not provide a person of 

ordinary skill in the art “with a meaning that is reasonably certain and defines objective boundaries” of the claim 

scope. Id. The court rejected Sonix’s argument that 

“visually negligible” means “something that may be 

visible, but does not interfere with the user’s perception of 

other visual information on a surface,” concluding that

defining the term “as reliant on the user’s perception 

provides no objective standard by which to measure the 

scope of the term—the user’s perception becomes the 

measure and this is insufficient.” Id. (citing Datamize, 

LLC v. Plumtree Software, Inc., 417 F.3d 1342, 1351 (Fed. 

Cir. 2005)). 

The district court also rejected Sonix’s attempts to rely on other portions of the written description. For example, the court determined that the instruction that the 

graphical micro-units “must be so tiny that only a microscope apparatus can detect it,” ’845 patent, col. 3 ll. 24–25, 

failed to provide reasonable certainty because the written 

description “contains no information . . . regarding what 

type of microscope apparatus or what level of magnification the user would need.” Opinion, 2015 WL 8153600, at 

*14. The court similarly rejected Sonix’s reliance on the 

differentiability, brightness, and homogeneity requirements because they lacked “the necessary detail to make 

[them] meaningful.” Id. Finally, the court rejected the 

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prosecution and reexamination history as not providing 

additional guidance. Id. at *15. 

Although the district court determined that it was 

“not necessary” to consult the extrinsic evidence, it nonetheless concluded that the extrinsic evidence “highlights 

the problem with the subjective nature of the ‘visually 

negligible’ claim term.” Id. The court noted, for example, 

that although the experts applied the term to the prior 

art, they did not provide any standard by which to measure negligibility aside from their “subjective belief.” Id. 

The district court then reviewed recent cases from the 

Supreme Court and this court, and determined that the 

present case was more similar to those concluding that 

claims were invalid as indefinite than to those holding 

otherwise. See id. at *15–17 (citing Nautilus v. Biosig 

Instruments, Inc., 134 S. Ct. 2120, 2129 (2014); Interval 

Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1368–74 (Fed. 

Cir. 2014); Enzo Biochem, Inc. v. Applera Corp., 599 F.3d 

1325, 1336 (Fed. Cir. 2010); Datamize, 417 F.3d at 1349–

54).

The district court therefore entered judgment against 

Sonix and for Appellees on December 8, 2015. J.A. 1–2. 

Sonix timely appealed. We have jurisdiction pursuant to 

28 U.S.C. § 1295(a)(1). 

DISCUSSION

At the outset, there is a dispute relating to the standard of review to be applied to the present case. Sonix 

argues that our review is entirely de novo, because the 

district court indicated that it was unnecessary to address 

the extrinsic evidence and did not make any factual 

findings based thereon. Appellees respond that the 

district court made underlying findings that “visually 

negligible” is subjective and that it lacks an objectivelymeasurable standard. 

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10 SONIX TECH. CO. v. PUBL’NS INT’L, LTD. 

We agree with Sonix that we review a district court’s 

determination that a claim is invalid as indefinite under 

35 U.S.C. § 112 ¶ 2 de novo, although, as with claim 

construction, any factual findings by the district court 

based on extrinsic evidence are reviewed for clear error. 

Cox Commc’ns, Inc. v. Sprint Commc’n Co., 838 F.3d 

1224, 1228 (Fed. Cir. 2016) (citing Teva Pharm. USA, Inc. 

v. Sandoz, Inc., 135 S. Ct. 831, 840–42 (2015) (“Teva I”)). 

To trigger clear error review, “it is not enough that the 

district court may have heard extrinsic evidence during a 

claim construction proceeding—rather, the district court 

must have actually made a factual finding . . . .” CardSoft, LLC v. VeriFone, Inc., 807 F.3d 1346, 1350 (Fed. Cir. 

2015) (citations omitted). Moreover, “[a] party cannot 

transform into a factual matter the internal coherence 

and context assessment of the patent simply by having an 

expert offer an opinion on it. The internal coherence and 

context assessment of the patent, and whether it conveys 

claim meaning with reasonable certainty, are questions of 

law.” Teva Pharm. USA, Inc. v. Sandoz, Inc., 789 F.3d 

1335, 1342 (Fed. Cir. 2015) (“Teva II”). 

The district court expressly explained that the extrinsic evidence was “not necessary for [its] consideration” of 

the indefiniteness issue. Opinion, 2015 WL 8153600, at 

*15. Moreover, the district court’s conclusions of subjectivity and lack of an objective standard are not findings 

subject to clear error review; instead, they are conclusions 

relating to the meaning of the intrinsic evidence, and 

whether it conveys claim meaning with reasonable certainty. See Teva II, 789 F.3d at 1342. Such conclusions 

cannot be transformed into factual matters “simply by 

having an expert offer an opinion on [them].” Id. 

I. INDEFINITENESS

Sonix argues that the district court erred in concluding that “visually negligible” renders the asserted claims 

invalid as indefinite. Specifically, Sonix argues that the 

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requirements and examples in the written description 

would have allowed a skilled artisan to know the scope of 

the claimed invention with reasonable certainty and 

establish that the term depends on human perception, not 

opinion. This conclusion is supported, Sonix contends, by 

the consistent manner in which “visually negligible” has 

been applied during initial examination, both reexaminations, and the majority of the district court litigation. 

Appellees respond that visual negligibility does not 

have an objective standard because it depends on the 

“vagaries of any one person’s opinion,” Datamize, 417 F.3d 

at 1350, and is therefore indefinite. Appellees contend 

that the written description would not allow a skilled 

artisan to understand the scope of the claims with reasonable certainty, and that the ability of experts to apply 

the term does not provide an objective standard.

We agree with Sonix that a skilled artisan would understand, with reasonable certainty, what it means for an 

indicator in the claimed invention to be “visually negligible.” The intrinsic evidence supports, and the extrinsic 

evidence is consistent with, this conclusion.

Section 112 requires that a patent specification “conclude with one or more claims particularly pointing out 

and distinctly claiming the subject matter which the 

applicant regards as his invention.” The Supreme Court 

has read this provision to require that “a patent’s claims, 

viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the 

invention with reasonable certainty.” Nautilus, 134 S. Ct. 

at 2129. Indefiniteness must be proven by clear and 

convincing evidence. See Teva II, 789 F.3d at 1345. 

The § 112 ¶ 2 requirement strikes a “delicate balance” 

between “the inherent limitations of language” and 

providing “clear notice of what is claimed.” Nautilus, 134 

S. Ct. at 2129 (internal citations omitted). Even so, the 

Supreme Court has recognized that “absolute precision is 

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unattainable.” Id. “[T]he certainty which the law requires in patents is not greater than is reasonable, having 

regard to their subject-matter.” Id. (quoting Minerals 

Separation, Ltd. v. Hyde, 242 U.S. 261, 270 (1916) (internal quotation marks omitted)). 

Because language is limited, we have rejected the 

proposition that claims involving terms of degree are 

inherently indefinite. Interval Licensing, 766 F.3d at 

1370. Thus, “a patentee need not define his invention 

with mathematical precision in order to comply with the 

definiteness requirement.” Invitrogen Corp. v. Biocrest 

Mfg., L.P., 424 F.3d 1374, 1384 (Fed. Cir. 2005) (citation 

omitted). Indeed, “[c]laim language employing terms of 

degree has long been found definite where it provided 

enough certainty to one of skill in the art when read in 

the context of the invention.” Interval Licensing, 766 F.3d 

at 1370 (citing Eibel Process Co. v. Minn. & Ont. Paper 

Co., 261 U.S. 45, 65–66 (1923)). 

Accordingly, we have held that the clause “not interfering substantially” did not render a claim invalid as 

indefinite. Enzo, 599 F.3d at 1336.2 In that case, we 

reasoned that the intrinsic evidence provided guidance as 

to the scope of the claims, including, inter alia, examples 

of noninterfering structures and criteria for their selection. Id. at 1334–35. This guidance allowed a skilled 

artisan to compare a potentially infringing product “with 

the examples in the specification to determine whether 

interference . . . is substantial.” Id. at 1336. 

We have found terms of degree indefinite, however, 

when such guidance is lacking. For example, Datamize

2 Although Enzo was decided before the introduction of the “reasonable certainty” standard, we have relied 

on it in our post-Nautilus decisions. See, e.g., Interval 

Licensing, 766 F.3d at 1370. 

 

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involved claims to an “aesthetically pleasing” look and feel 

for interface screens. 417 F.3d at 1348–49. We determined that such language rendered the claim indefinite 

because, although the written description did detail 

various elements that might affect whether a screen was 

aesthetically pleasing (such as button styles and sizes), it 

“provide[d] no guidance to a person making aesthetic 

choices such that their choices will result in an ‘aesthetically pleasing’ look and feel of an interface screen.” Id. at 

1352. Without such guidance, the claim did “not just 

include a subjective element, it [wa]s completely dependent on a person’s subjective opinion.” Id. 

Similarly, Interval Licensing involved a claim related 

to displaying content “in an unobtrusive manner that does 

not distract a user.” 766 F.3d at 1368. We observed that 

the term was “a term of degree,” id. at 1370, “purely 

subjective,” id. at 1371, and that the claim language 

offered “no objective indication of the manner in which 

content images are to be displayed to the user,” id. We 

refused to limit the “facially subjective claim term” to the 

single example in the written description because, without more information, “a skilled artisan is still left to 

wonder what other forms of display are unobtrusive and 

non-distracting . . . thus leaving the skilled artisan to 

consult the ‘unpredictable vagaries of any one person’s 

opinion.’” Id. at 1373–74 (quoting Datamize, 417 F.3d at 

1350). 

As indefiniteness analysis involves general claim construction principles, we begin with the language of the 

claims of the ’845 patent. See Enzo, 599 F.3d 1332. We do 

agree with the district court that the claim language itself 

does not unmistakably make clear the scope of “visually 

negligible”; however, we disagree with the conclusion, and 

Appellees’ argument, that the term is “purely subjective,” 

Opinion, 2015 WL 8153600, at *13, in the same manner 

as “aesthetically pleasing” in Datamize and “in an unobCase: 16-1449 Document: 62-2 Page: 13 Filed: 01/05/2017
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trusive manner that does not distract a user” in Interval 

Licensing. 

Datamize and Interval Licensing involved terms that 

were subjective in the sense that they turned on a person’s tastes or opinion. “Aesthetically pleasing” implicates matters of taste or preference; whether something is 

aesthetically pleasing is a value judgment that inherently 

varies from person to person. “In an unobtrusive manner 

that does not distract” similarly implicates a person’s 

individual focus, concentration, attentiveness, or similar 

mental state at a given moment, or even opinions, affecting what is or is not distracting. The question whether 

something is “visually negligible” or whether it interferes 

with a user’s perception, however, involves what can be 

seen by the normal human eye. This provides an objective baseline through which to interpret the claims. See

Warsaw Orthopedic, Inc. v. NuVasive, Inc., 778 F.3d 1365, 

1371 (Fed. Cir. 2015), cert. granted, judgment vacated sub 

nom. Medtronic Sofamor Danek USA, Inc. v. NuVasive, 

Inc., 136 S. Ct. 893 (2016), and opinion reinstated in 

relevant part, 824 F.3d 1344, 1346 (Fed. Cir. 2016). Thus, 

although the term may be a term of degree, it is not 

“purely subjective.” 

We turn next to the written description, to determine 

whether there is some standard in the written description 

for measuring visual negligibility. See Enzo, 599 F.3d at 

1332. Our prior cases establish that the written description is key to determining whether a term of degree is 

indefinite. In Enzo, for example, the written description

included examples of noninterfering structures and the 

procedures for selecting them; we reasoned that the 

examples and procedures provided guidance and points of 

comparison for skilled artisans. Id. at 1335–36. The one 

example provided in the written description at issue in 

Interval Licensing, in contrast, was not accompanied by 

sufficient detail to render the claim scope reasonably 

certain. 766 F.3d at 1372. In Datamize, the written 

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description did not contain any examples of an “aesthetically pleasing” interface, nor did it “explain what factors a 

person should consider when selecting a feature” to lead 

to an aesthetically pleasing result. 417 F.3d at 1352. 

On the other hand, the ’845 patent contains considerably more detail than Datamize or Interval Licensing. As

explained previously, the written description of the ’845 

patent includes: (1) a general exemplary design for a 

visually-negligible indicator, ’845 patent, col. 3 ll. 13–20; 

(2) “requirements for the graphical indicators being 

negligible to human eyes,” id. col. 4 l. 60–col. 5 l. 5; and 

(3) two specific examples of visually-negligible indicators, 

id. col. 5 ll. 6–15. That there are examples at all distinguishes this case from Datamize, and that the written 

description contains an additional example and specific 

requirements distances this case from Interval Licensing. 

Instead, the level of detail provided in the written description is closer to that provided in Enzo: These are 

statements that provide guidance on how to create visually-negligible indicators, and specific examples that provide points of comparison for the result. 

Appellees criticize what they see as the written description’s low level of detail. Specifically, they argue that 

the examples and requirements in the written description

cannot be translated to an objective standard for the 

claim’s scope because they, too, are subjective. We disagree. Just as the patent in Enzo included “examples of 

suitable linkage groups,” 599 F.3d at 1334, the ’845 patent includes examples of visually-negligible indicators, 

’845 patent, col. 5 ll. 6–15. Just as the patent in Enzo

provided “some criteria for selecting [linkage groups that 

did not substantially interfere],” 599 F.3d at 1334, the 

’845 patent includes the differentiability, brightness, and 

homogeneity “requirements for the graphical indicators 

being negligible to human eyes,” ’845 patent, col. 4 l. 60–

col. 5 l. 5. The guidance in Enzo allowed a skilled artisan 

to compare a potentially infringing product “with the 

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examples in the specification to determine whether interference . . . is substantial,” 599 F.3d at 1336; similarly, an 

accused infringer could compare the examples and criteria 

from the written description of the ’845 patent to determine whether an indicator is visually negligible. Moreover, Appellees have not provided evidence that human 

perception varies so significantly that reliance on it as a 

standard renders the claims indefinite. See Warsaw, 778 

F.3d at 1371. Thus, as in Enzo, the written description of 

the ’845 patent supports the conclusion that a skilled 

artisan would have understood the term with reasonable 

certainty.

Other aspects of this case also make reversal compelling. The prosecution history of the ’845 patent, which 

includes the reexamination history, see Info-Hold, Inc. v. 

Applied Media Techs. Corp., 783 F.3d 1262, 1266 (Fed. 

Cir. 2015), supports that conclusion. No one involved in 

either the first or the second reexamination had any 

apparent difficulty in determining the scope of “visually 

negligible.” During the first reexamination, SunPlus 

repeatedly argued that the prior art disclosed visuallynegligible graphical indicators without any apparent 

uncertainty as to the meaning or scope of the term, and no 

apparent difficulty applying it to the references at issue. 

See, e.g., J.A. 795, 800, 801, 811, 823, 835, 844, 849–50, 

854, 864, 876. During the second reexamination, the 

examiner was able to understand and apply the term in 

performing a search for prior art and make an initial 

rejection. See J.A. 2312–13. Moreover, Serjersen was 

able to understand both the claims and written description with sufficient certainty to (1) replicate the claimed 

indicator; and (2) opine regarding whether it, and the 

indicators of Lamoure and Priddy, were visually negligible. See J.A. 2338–44, 5313–25. Thus, he was readily 

able to differentiate between which indicators were and 

which were not visually negligible. Finally, the examiner 

understood the import of Serjersen’s results well enough 

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to withdraw the rejections in response, indicating that he 

was able to differentiate between indicators as well. J.A. 

2363–65. Again, GeneralPlus, Sonix, and the USPTO did 

not express any uncertainty as to the scope of “visually 

negligible,” or encounter any apparent difficulty in applying the term to the references.

Appellees challenge this evidence as well, arguing 

that the fact that the experts applied the term does not 

mean that they used or could determine an objective 

standard. Although Appellees are correct that application 

by the examiner and an expert do not, on their own, 

establish an objective standard, they nevertheless provide

evidence that a skilled artisan did understand the scope 

of this invention with reasonable certainty. 

The extrinsic evidence, to the extent that it is necessary in this case, does not counsel otherwise. Appellees 

apparently understood the meaning of “visually negligible” from the beginning of the litigation. Their initial 

invalidity contentions did not argue that the “visually 

negligible” was indefinite, and neither did their final 

contentions. Indeed, at no point before Dr. Ashok’s deposition did they contend that “visually negligible” was 

indefinite, even though they contended that twenty-eight 

other terms were indefinite. That Appellees themselves 

did not question the clarity of “visually negligible” in the 

first several years of litigation supports the conclusion 

that the term could be understood with reasonable certainty. 

Appellees’ other actions during litigation also reflect 

that they understood “visually negligible.” They initially 

argued for a specific construction of the term, but later 

abandoned their attempt in favor of an ordinary-meaning 

construction. The parties’ experts also had no difficulty in 

applying “visually negligible.” Dr. Ashok and Dr. Engels 

repeatedly applied the term to the references and the 

accused products. Although Appellees again argue that 

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18 SONIX TECH. CO. v. PUBL’NS INT’L, LTD. 

this does not establish an objective standard, continued 

application by the experts in this case further supports

the conclusion that a skilled artisan did understand the 

term with reasonable certainty.

Appellees’ repeatedly cite Dr. Ashok’s responses during his deposition. Appellees asked Dr. Ashok to define

“visually negligible,” a term for which he had given no 

previous definition, and which Appellees had previously 

agreed did not need a construction. But it is unsurprising 

that Dr. Ashok indicated that he was unaware of a “technical standard” for the term, J.A. 4756 at 51:9–11; as 

Appellees had agreed to an ordinary-meaning construction, there was no reason for him to attempt to determine

one. Even so, Dr. Ashok did not opine that a skilled 

artisan would have any trouble understanding the term

or that the claims were indefinite, and he observed that 

he thought that his assessment of what was visually 

negligible would likely be representative. See J.A. 4755–

56. Dr. Engels, Appellees’ own expert, also did not opine 

that the claims were indefinite or that a skilled artisan 

would not have understood the term; instead, he provided 

a one-sentence statement that “visually negligible” is 

subjective and that there was no objective test to define it. 

See J.A. 3709. Dr. Engels did not detail any basis for this 

conclusion, instead simply stating that it was “based on 

Dr. Ashok’s testimony.” Id. In light of the intrinsic 

evidence, this ambiguous testimony is not persuasive. 

Our holding in this case does not mean that the existence of examples in the written description will always 

render a claim definite, or that listing requirements 

always provide sufficient certainty. Neither does the fact 

that an expert has applied a contested claim term without 

difficulty render a claim immune from an indefiniteness 

challenge. As always, whether a claim is indefinite must 

be judged “in light of the specification and prosecution 

history” of the patent in which it appears. Interval Licensing, 766 F.3d at 1369. We simply hold that “visually 

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SONIX TECH. CO. v. PUBL’NS INT’L, LTD. 19

negligible” is not a purely subjective term and that, on 

this record, the written description and prosecution 

history provide sufficient support to inform with reasonable certainty those skilled in the art of the scope of the 

invention. The examiner’s knowing allowance of claims 

based on the term that is now questioned, plus the acceptance of the term by both parties’ experts, force us to 

the conclusion that the term “visually negligible” is not 

indefinite. Accordingly, we reverse the district court’s 

conclusion that the asserted claims are invalid as indefinite.

Because we hold that the district court erred in concluding that the asserted claims are indefinite, we need 

not, and do not, reach Sonix’s alternative arguments for 

reversal.

CONCLUSION

We have considered the remaining arguments, but 

find them unpersuasive. For the foregoing reasons, the 

decision of the district court is reversed. 

REVERSED

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