NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________ 

SARIF BIOMEDICAL LLC,

Plaintiff-Appellee

v.

BRAINLAB, INC., BRAINLAB AG, BRAINLAB 

MEDIZINISCHE COMPUTERSYSTEME GMBH,

Defendants-Appellants

______________________ 

2017-1103

______________________ 

Appeal from the United States District Court for the 

District of Delaware in No. 1:13-cv-00846-LPS, Chief 

Judge Leonard P. Stark.

______________________ 

Decided: March 21, 2018

______________________ 

 PAUL ANTHONY KROEGER, Russ August & Kabat, Los 

Angeles, CA, argued for plaintiff-appellee. Also represented by MARC AARON FENSTER, JEFFREY ZHI YANG LIAO. 

 JAY CAMPBELL, Tucker Ellis LLP, Cleveland, OH, 

argued for defendants-appellants. Also represented by 

MARISSA MEGAN ENNIS, JOSHUA MICHAEL RYLAND; SANDRA 

J. WUNDERLICH, St. Louis, MO.

______________________ 
2 SARIF BIOMED. LLC v. BRAINLAB, INC. 

Before REYNA, WALLACH, and HUGHES, Circuit Judges.

WALLACH, Circuit Judge.

Appellee Sarif Biomedical LLC (“Sarif”) sued Appellants Brainlab, Inc., Brainlab AG, and Brainlab 

Medizinische Computersysteme GmbH (collectively, 

“Brainlab”) in the U.S. District Court for the District of 

Delaware (“District Court”), alleging infringement of, 

inter alia, claims 1–9 of U.S. Patent No. 5,755,725 (“the 

’725 patent”). Following an order on claim construction

adverse to Sarif, see Sarif Biomed. LLC v. Brainlab, Inc. 

(Sarif I), No. 13-846-LPS, 2015 WL 5072085, at *10 (D. 

Del. Aug. 26, 2015), the parties jointly stipulated to final 

judgment of invalidity and noninfringement, and Brainlab 

filed a motion for attorney fees pursuant to 35 U.S.C. 

§ 285 (2012). The District Court denied Brainlab’s Motion 

for Attorney Fees. Sarif Biomed. LLC v. Brainlab, Inc.

(Sarif II), No. 13-846-LPS, 2016 WL 5422479, at *1 (D. 

Del. Sept. 27, 2016) (Order on Attorney Fees). 

Brainlab appeals the denial of attorney fees. We have 

jurisdiction pursuant to 28 U.S.C. § 1295(a)(1) (2012). We 

affirm. 

BACKGROUND

I. The ’725 Patent

Entitled “Computer-Assisted Microsurgery Methods 

and Equipment,” the ’725 patent “relates to an installation for computer-assisted stereotactic microsurgery” that

includes, inter alia, the use of a microsurgery tool-support 

and an image data base. ’725 patent col. 1 ll. 7–8; see id.

col. 2 l. 62–col. 3 l. 2. The ’725 patent purports “to assure 

a correlation between the digital images obtained by 

means of a medical imaging system with the patient so as 

to provide the surgeon with the data intended to guide his 

operative strategy in real time.” Id. col. 2 ll. 42–46.
SARIF BIOMED. LLC v. BRAINLAB, INC. 3

Claim 1, from which claims 2–9 directly or indirectly 

depend, is the only independent claim on appeal. It 

relates to “[a] computer-assisted microsurgery installation,” which, relevant here, includes “(e) means for determining coordinates of the tool in the fixed reference 

system Rc based on data from the image data base” (“limitation (e)”). Id. col. 10 l. 62, col. 11 ll. 18–20.1 

II. The Relevant Proceedings

On May 14, 2013, Sarif filed its complaint in the District Court. J.A. 988. While the District Court litigation 

was pending, Brainlab petitioned the U.S. Patent and 

Trademark Office (“USPTO”) for inter partes review of 

Sarif’s ’725 patent. See Brainlab, AG v. Sarif Biomed. 

LLC, No. IPR2014-00753, 2014 WL 5788571, at *1 

(P.T.A.B. Nov. 4, 2014). The USPTO’s Patent Trial and 

Appeal Board (“PTAB”) declined to institute inter partes 

review for claims 1–9 on the basis that claim 1, and 

therefore attendant claims 2–9, were indefinite because 

the specification lacked a supporting structure. See id. at 

*1, *6. Sarif ultimately disclaimed remaining claims 10 

and 11, thereby terminating the PTAB proceedings, but 

Sarif continued to pursue claims 1–9 in the District Court 

litigation. 

 

1 The District Court construed limitation (e) as a 

means-plus-function limitation, see Sarif I, 2015 WL 

5072085, at *9, and the parties do not dispute that limitation (e) is a mean-plus-function limitation, see, e.g., Appellants’ Br. 7; Appellee’s Br. 4; see also 35 U.S.C. § 112 ¶ 6 

(2006) (“An element in a claim for a combination may be 

expressed as a means or step for performing a specified 

function without the recital of structure, material, or acts 

in support thereof, and such claim shall be construed to 

cover the corresponding structure, material, or acts described in the specification and equivalents thereof.” 

(emphases added)).
4 SARIF BIOMED. LLC v. BRAINLAB, INC. 

On August 26, 2015, the District Court issued Sarif I

and determined that the specification lacked a supporting 

structure, such that limitation (e) was indefinite. See 

2015 WL 5072085, at *9. The District Court explained 

that, “[w]hile . . . the specification teaches detailed formulas for transitioning from one frame to another, there is 

no clear structural link for the cameras to use the image 

database to determine the coordinates of the tool—which 

is the disclosed function.” Id. at *10. On October 1, 2015, 

Sarif and Brainlab filed a joint stipulation of judgment of

invalidity and noninfringement, stipulating that, in light 

of the District Court’s claim construction order, “claims 1 

through 9 of the [’]725 patent are invalid due to indefiniteness.” J.A. 983. The District Court entered judgment 

of invalidity and noninfringement. J.A. 999. 

On October 19, 2015, Brainlab moved for attorney fees 

pursuant to § 285. J.A. 7. The District Court denied 

Brainlab’s Motion for Attorney Fees and determined that 

the case was not “exceptional,” “find[ing] no basis to 

conclude that this case should not have been brought.” 

Sarif II, 2016 WL 5422479, at *1. The District Court 

found that “[Sarif] had a good faith, though ultimately 

incorrect, belief that its claims were not indefinite,” 

noting that, “[a]t each stage of the litigation, [Sarif] 

provided detailed arguments, grounded in the intrinsic 

evidence, in support of its proposed constructions” and 

“obtained expert opinion which supported its constructions.” Id. at *2 (footnote omitted). The District Court 

rejected Brainlab’s arguments that “[Sarif]’s conduct 

following the PTAB proceeding constituted an unreasonable approach to litigation or demonstrate[d] that [Sarif]’s 

case was extraordinarily weak.” Id. 

DISCUSSION

I. Standard of Review and Legal Standard

We review “all aspects of a district court’s § 285 determination for abuse of discretion.” Highmark Inc. v. 
SARIF BIOMED. LLC v. BRAINLAB, INC. 5

Allcare Health Mgmt. Sys., Inc., 134 S. Ct. 1744, 1747 

(2014). A district court abuses its discretion where, inter 

alia, it “bases its ruling on an erroneous view of the law or 

on a clearly erroneous assessment of the evidence.” 

Rothschild Connected Devices Innovations, LLC v. Guardian Prot. Servs., Inc., 858 F.3d 1383, 1387 (Fed. Cir. 2017)

(quoting Highmark, 134 S. Ct. at 1748 n.2). “A factual 

finding is clearly erroneous if, despite some supporting 

evidence, we are left with the definite and firm conviction 

that a mistake has been made.” Id. (internal quotation 

marks and citation omitted).

“We apply Federal Circuit caselaw to the § 285 analysis, as it is unique to patent law.” Digeo, Inc. v. Audible, 

Inc., 505 F.3d 1362, 1366 (Fed. Cir. 2007) (citation omitted); see, e.g., AdjustaCam, LLC v. Newegg Inc., 861 F.3d 

1353, 1359 (Fed. Cir. 2017) (relying on Federal Circuit 

precedent). By statute, a district court “in exceptional 

cases may award reasonable attorney fees to the prevailing party.” 35 U.S.C. § 285. “An ‘exceptional’ case is 

simply one that stands out from others with respect to the 

substantive strength of a party’s litigating position (considering both the governing law and the facts of the case) 

or the unreasonable manner in which the case was litigated.” Octane Fitness, LLC v. Icon Health & Fitness, 

Inc., 134 S. Ct. 1749, 1756 (2014). The Supreme Court 

has instructed that a district court should consider “the 

totality of the circumstances,” including a party’s “motivation.” Id. at 1756, 1756 n.6 (internal quotation marks and 

citation omitted). 

II. The District Court Did Not Abuse Its Discretion in 

Making Its Exceptional-Case Determination

Brainlab argues the District Court abused its discretion in failing to award attorney fees. See Appellants’ Br. 

34–56. Brainlab contends that Sarif’s unmeritorious 

construction of limitation (e) and modifications to its 

construction throughout the course of the proceedings 
6 SARIF BIOMED. LLC v. BRAINLAB, INC. 

demonstrate that the District Court erred in evaluating 

the strength and reasonability of Sarif’s litigating position. Id. at 37–49. Brainlab also claims the District 

Court failed to account for the totality of the circumstances, including Sarif’s improper motivations in maintaining 

this suit against Brainlab. See id. at 49–56. We disagree. 

A. Substantive Strength 

The District Court properly evaluated the substantive 

strength of Sarif’s case. The District Court found that 

Sarif acted in “good faith” in part because, “[a]t each stage 

of the litigation, [Sarif] provided detailed arguments, 

grounded in the intrinsic evidence, in support of its proposed constructions” and “obtained expert opinion which 

supported its constructions.” Sarif II, 2016 WL 5422479, 

at *2 (footnote omitted).2 Supporting its constructions 

with citations to the specification and expert testimony, 

Sarif identified two supporting structures for limitation 

(e)—“a computer . . . using algorithms,” J.A. 750 (citing

J.A. 777–79 (Sarif’s expert declaration)), 1009–10 (joint 

claim construction chart) (citing ’725 patent col. 7 l. 66–

col. 9 l. 60); see J.A. 898, 913–14 (Sarif’s expert testimony), and the specification’s recital of “at least two acquisition cameras,” J.A. 750 (citing J.A. 776–77 (Sarif’s expert 

declaration)), 1009–10 (joint claim construction chart) 

(citing ’725 patent col. 3 ll. 39–43); see J.A. 898 (Sarif’s 

expert testimony). The District Court’s ultimate disagreement with Sarif’s proposed construction does not, on 

 

2 Brainlab attempts to impugn the District Court’s 

finding of good faith by arguing that a declaration provided by Sarif’s counsel is conclusory. See Appellants’ 

Br. 39–40. Whether Brainlab is correct, the District 

Court never relied on the contested declaration. See 

generally Sarif II, 2016 WL 5422479. We will not find an 

abuse of discretion based on purportedly insufficient 

evidence that was not considered below.
SARIF BIOMED. LLC v. BRAINLAB, INC. 7

its own, render Sarif’s case substantively weak. See SFA 

Sys., LLC v. Newegg Inc., 793 F.3d 1344, 1348 (Fed. Cir. 

2015) (distinguishing Octane’s “substantive strength of 

the party’s litigation position” standard from “the correctness or eventual success of that position” (internal quotation marks and citation omitted)).

Moreover, the District Court properly determined

that, “as a whole,” Sarif’s claim construction arguments 

were not “inconsistent with those [it] took before the 

PTAB.” Sarif II, 2016 WL 5422479, at *2. Before the 

PTAB, Sarif proffered a similarly well-supported construction. Sarif identified as a supporting structure for 

limitation (e) “an algorithm or software running on a 

computer system.” J.A. 90; see J.A. 91 (citing ’725 patent 

col. 10 ll. 52–55). Although Sarif modified its position 

before the District Court by also relying on the specification’s “at least two acquisition cameras,” Sarif consistently relied on the algorithms on the computer system as a 

supporting structure in both constructions and justified

its change in construction through reliance on its expert’s 

testimony and the ’725 patent’s specification, as detailed 

above. Compare J.A. 90–91, with J.A. 750, and 

J.A. 1009–10.

Brainlab’s counterarguments are ultimately unpersuasive under our standard of review. First, Brainlab

avers that the PTAB’s decision not to institute an inter 

partes review for claims 1–9, after stating these claims 

“cannot be construed” based on a likelihood that they are 

indefinite, Brainlab, 2014 WL 5788571, at *5, demonstrates the weakness of Sarif’s position, as it is an important “objective indicator[] of the invalidity of the ’725 

patent,” Appellants’ Br. 42. Brainlab places too much 

significance on the PTAB’s determination. The PTAB 

does not have authority to institute an inter partes review 

under § 112. See 35 U.S.C. § 311(b). Therefore, as Brainlab admitted, any conclusion regarding indefiniteness is 

dicta. See Oral Arg. at 27:31–40, http://oralarguments.
8 SARIF BIOMED. LLC v. BRAINLAB, INC. 

cafc.uscourts.gov/default.aspx?fl=2017-1103.mp3 (“Claims 

1–9 were found to be indefinite . . . [by] the PTAB, in its 

dicta, . . . .”); see also id. at 28:58–31:06. 

Second, Brainlab argues Sarif’s proposed construction 

is weak because portions of Sarif’s expert testimony 

appear to undermine its ultimate construction. See 

Appellants’ Br. 42–44 (citing, inter alia, J.A. 876–77, 898). 

However, the District Court is entitled to weigh the 

credibility of an expert’s testimony, see Celsis In Vitro, 

Inc. v. CellzDirect, Inc., 664 F.3d 922, 929 (Fed. Cir. 2012) 

(“The district court has wide discretion to weigh expert 

credibility.” (citation omitted)), and these isolated statements are insufficient to demonstrate that the District 

Court abused its discretion in finding that, on balance, 

the “expert opinion . . . supported [Sarif’s] constructions,” 

Sarif II, 2016 WL 5422479, at *2 (footnote omitted); see 

J.A. 898–900 (providing full expert testimony, which

defends Sarif’s construction); see also Romag Fasteners, 

Inc. v. Fossil, Inc., 866 F.3d 1330, 1341 (Fed. Cir. 2017) 

(requiring, under § 285, a party’s position to be “objectively unreasonable,” rather than merely “weak,” for an 

award of attorney fees). 

Third, throughout its brief, Brainlab argues the District Court “fail[e]d to make findings of fact in support of 

its conclusion that Sarif’s case was not unusually weak” 

and “ignored . . . overwhelming evidence.” Appellants’ 

Br. 37; see id. at 37–42. However, we have recognized 

that “[t]he trial judge [i]s in the best position to understand and weigh the[] issues,” and the District Court 

“ha[d] no obligation to write an opinion that reveals [his] 

assessment of every consideration.” Univ. of Utah v. MaxPlanck-Gesellschaft zur Foerderung der Wissenschaften 

e.V., 851 F.3d 1317, 1323 (Fed. Cir. 2017). Upon our 

review of the record, we find the District Court adequately 

considered the facts, and we are not left with a “definite 

and firm conviction that a mistake has been made.” 
SARIF BIOMED. LLC v. BRAINLAB, INC. 9

Rothschild, 858 F.3d at 1387 (internal quotation marks 

and citation omitted).

B. Unreasonable Manner and Other Considerations

The District Court also did not clearly err in considering the reasonableness of the manner in which Sarif 

litigated this case or any other circumstances of this case. 

Although Sarif modified its claim construction position 

from the PTAB to the District Court, the District Court 

correctly explained that 

[i]t can . . . be reasonable for a party to propose 

different constructions in PTAB and District 

Court proceedings, as the PTAB must give claims 

terms their “broadest reasonable construction,” 

whereas District Courts give them the meaning 

they would have to a “person of ordinary skill in 

the art at the time of the invention.” 

Sarif II, 2016 WL 5422479, at *2 (citing Cuozzo Speed 

Techs., LLC v. Lee, 136 S. Ct. 2131, 2142 (2016)). Brainlab claims the District Court committed legal error because it did not consider whether this stated standard 

applies to a means-plus-function clause such as limitation 

(e). See Appellants’ Br. 45–46 (citing In re Donaldson Co., 

16 F.3d 1189, 1194–95 (Fed. Cir. 1994) (“[T]he ‘broadest 

reasonable interpretation’ that an examiner may give 

means-plus-function language is that statutorily mandated in [35 U.S.C. § 112 ¶ 6].”)). Brainlab fails to appreciate 

that claim construction for means-plus-function limitations is no different in terms of the standard used than for 

non-means-plus-function terms. See In re Donaldson, 16 

F.3d at 1194 (“[O]ur holding [that § 112 ¶ 6 applies to 

means-plus-function terms regardless of forum] does not 

conflict with the principle that claims are to be given their 

‘broadest reasonable interpretation’ during prosecution.”). 

The District Court’s reliance on the general legal principles of claim construction, therefore, was not misplaced. 
10 SARIF BIOMED. LLC v. BRAINLAB, INC. 

Brainlab also has failed to demonstrate that Sarif’s 

motivations and actions as a whole were improper. See 

Appellants’ Br. 53–56. Although we have stated “that a 

pattern of litigation abuses characterized by the repeated 

filing of patent infringement actions for the sole purpose 

of forcing settlements, with no intention of testing the 

merits of one’s claims, is relevant to a district court’s 

exceptional[-]case determination under § 285,” SFA Sys., 

793 F.3d at 1350, the District Court considered Brainlab’s 

evidence and concluded Brainlab “ha[d] not demonstrated 

that this is a ‘nuisance suit’” because “[Sarif]’s status as a 

non-practicing entity, the language of the press releases 

directed toward its investors, its decision to allege infringement against several other entities, and its decision 

to settle other cases, do not combine to establish that this 

case was always ‘meritless’ or ‘predatory,’” Sarif II, 2016 

WL 5422479, at *2 (emphasis added). Importantly, Sarif 

did not delay in its litigation tactics. For instance, the 

District Court acknowledged that Sarif disclaimed claims 

10–11, soon after the PTAB instituted an inter partes 

review of those claims, and Sarif decided not to pursue 

those claims in the District Court litigation. See id. at *1. 

Moreover, Sarif stipulated to judgment of invalidity and 

noninfringement a mere six days after the District Court 

found claims 1–9 indefinite. See J.A. 983. In sum, the 

District Court did not abuse its discretion. See SFA Sys., 

793 F.3d at 1352 (finding no abuse of discretion where 

“[appellant] failed to proffer sufficient evidence of a pattern of litigation misconduct by [appellee]”).

Brainlab claims the District Court erred “[b]y limiting 

itself to comparing Sarif’s conduct only to the cases ‘with 

which [the District Court] has been involved.’” Appellants’ 

Br. 49 (emphasis added) (quoting Sarif II, 2016 WL 

5422479, at *3). As we have explained above, the District 

Court properly determined that this case is not exceptional, grounding its reasoning in the correct legal standards 

and a proper assessment of the facts. Therefore, we 
SARIF BIOMED. LLC v. BRAINLAB, INC. 11

decline Brainlab’s invitation to find legal error “based 

upon [this] isolated statement stripped from its context.” 

Waymo LLC v. Uber Techs., Inc., 870 F.3d 1350, 1361 

(Fed. Cir. 2017) (internal quotation marks and citation 

omitted). 

CONCLUSION

We have considered Brainlab’s remaining arguments 

and find them unpersuasive. Accordingly, the Order on 

Attorney Fees of the U.S. District Court for the District of 

Delaware is

AFFIRMED