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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 ______________________ 

ADVANCED GROUND INFORMATION SYSTEMS, 

INC.,

Plaintiff-Appellant

v.

LIFE360, INC.,

Defendant-Appellee

______________________ 

2015-1732

______________________ 

Appeal from the United States District Court for the 

Southern District of Florida in No. 9:14-cv-80651-DMM, 

Judge Donald M. Middlebrooks.

______________________ 

Decided: July 28, 2016

______________________ 

GEORGE BADENOCH, Kenyon & Kenyon LLP, New 

York, NY, argued for plaintiff-appellant. Also represented by MARK ALEXANDER CHAPMAN, ROSE CORDERO PREY,

ALESSANDRA MESSING. 

DANIEL H. BREAN, The Webb Law Firm, Pittsburgh, 

PA, argued for defendant-appellee. Also represented by 

KENT E. BALDAUF, JR., BRYAN P. CLARK, CHRISTIAN D.

EHRET. 

______________________ 

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2 ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 

Before MOORE, MAYER, and WALLACH, Circuit Judges.

WALLACH, Circuit Judge. 

Advanced Ground Information Systems, Inc. (“AGIS”) 

appeals the decision of the United States District Court 

for the Southern District of Florida in Advanced Ground 

Information Systems, Inc. v. Life360, Inc., No. 14-cv-80651 

(S.D. Fla. Nov. 21, 2014) (J.A. 2–37), which found that

claims 3 and 10 of U.S. Patent No. 7,031,728 (“the ’728 

patent”) and claims 5 and 9 of U.S. Patent No. 7,672,681 

(“the ’681 patent”) (together, the “patents-in-suit”) invoke 

35 U.S.C. § 112, ¶ 6, and that the claims are indefinite 

under 35 U.S.C. § 112, ¶ 2 (2006).1 Although the district 

court found these claims indefinite, it did not address the 

issue of invalidity because Appellee, Life360, Inc., 

(“Life360”) did not request a finding of invalidity. The 

parties subsequently stipulated that these claims were 

invalid for indefiniteness, see J.A. 857, and the court 

entered its Final Judgment on May 12, 2015, see J.A. 1. 

For the reasons articulated below, we affirm the district 

court’s decision that the claims are indefinite, and accordingly conclude that the asserted claims are invalid. 

BACKGROUND

AGIS is a technology company, software developer, 

and military contractor, as well as the owner of the patents-in-suit. While the specifications of the patents-insuit differ from one another, the patents-in-suit relate to 

methods, devices, and systems for establishing a communication network for users (referred to as “participants” in 

 

1 Congress amended 35 U.S.C. § 112 when it passed 

the Leahy–Smith America Invents Act (“AIA”), and the 

amendments took effect on September 16, 2012. Pub. L. 

No. 112–29, § 4 125 Stat. 284, 296–97 (2011). Because the 

applications resulting in the patents-in-suit were filed 

before that date, we refer to the pre-AIA version of § 112.

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ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 3

the patents-in-suit) of mobile devices, such as cellular 

phones. 

I. The Patents-in-Suit

A. The ’728 Patent

The ’728 patent describes a cellular communication 

system that allows multiple cellular phone users to monitor others’ locations and statuses via visual display of 

such information on a map. ’728 patent, Abstract. For 

example, as illustrated in Figure 1 of the ’728 patent, 

users of a mobile device can see the locations of other 

users on the network (indicated by triangle 30 and square 

34 symbols): 

Id. fig.1. Symbols generated on the users’ cellular phones 

represent the latitude and longitude of other users. Id. 

col. 3 ll. 35–40. Users in the communication network may 

initiate a phone call, send text messages, or send data or 

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4 ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 

pictures with other users on the network by touching a 

symbol representative of the other users on the screen. 

Id. col. 11 ll. 12–13, 38–42. 

B. The ’681 Patent

The ’681 patent is a continuation-in-part of the ’728 

patent. It describes how “a designated administrator 

using a personal computer (PC) or other input device can 

reprogram all user and network participants’ cell phone 

devices to change, modify[,] or create new virtual switch 

names and new symbols for a different operating environment.” ’681 patent col. 2 ll. 3–7.

C. The Asserted Claims 

Claims 3 and 10 of the ’728 patent and claims 5 and 9 

of the ’681 patent (collectively, the “asserted claims”)

recite a “symbol generator” that generates symbols representing each user in the network on the display of a user’s 

cellular phone. Claim 3 of the ’728 patent is a system 

claim that recites a “symbol generator in [a central processing unit (‘CPU’)] that can generate symbols that 

represent each of the participants’ cell phones in the 

communication network on the display screen.” ’728 

patent col. 12 ll. 62–64 (emphasis added). Claim 5 of the 

’681 patent is a system claim similar to claim 3 of the ’728 

patent in all relevant respects, except that it recites a 

“symbol generator in [a] CPU that can generate symbols 

that represent each of the participants in the communication network on the display screen,” ’681 patent col. 12 ll. 

62–64 (emphasis added), as opposed to “each of the participants’ cell phones,” ’728 patent col. 12 l. 63. 

Claim 10 of the ’728 patent and claim 9 of the ’681 patent are apparatus claims that recite a “cellular phone for 

use in a communication network for a plurality of participants comprising . . . a symbol generator connected to [a]

CPU and [a] database for generating symbols on [a] touch 

screen display screen.” ’728 patent col. 14 ll. 28–47 (emCase: 15-1732 Document: 55-2 Page: 4 Filed: 07/28/2016
ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 5

phasis added); ’681 patent col. 13 l. 44–col. 14 l. 8 (same 

(emphasis added)). Both claims also recite that the 

cellular phone comprises “CPU Software.” See ’728 patent 

col. 14 ll. 48–49 (stating that the cellular phone comprises 

“CPU software for selectively polling other participants 

with a cellular phone”); ’681 patent col. 14 ll. 9–10 (stating 

that the cellular phone comprises “CPU software that 

causes the exchange of data with other participants with 

a cellular phone”). 

II. Procedural History

Life360 is a startup company and the creator of a 

smartphone software application (the “Life360 mobile 

app”). J.A. 2382. The Life360 mobile app was designed to 

allow families to stay better connected––it “runs on [a] 

mobile device to allow [users] to view [their] family members on a map, communicate with them, and receive alerts 

when [their] loved ones arrive at home, school[,] or work.” 

Product Tour, https://www.life360.com/tour/ (last visited 

July 26, 2016). On May 16, 2014, AGIS filed a complaint 

in the district court alleging that the Life360 mobile app 

infringed claims 3, 7, and 10 of the ’728 patent and claims 

1, 5, and 9 of the ’681 patent. See J.A. 2–3.

In response to AGIS’s Complaint, Life360 asserted 

that the claim terms “symbol generator” and “CPU software” in the asserted claims invoked means-plus-function 

claiming allowed under 35 U.S.C. § 112, ¶ 6, but the

terms failed to disclose adequate structure and, therefore, 

are indefinite under 35 U.S.C. § 112, ¶ 2. J.A. 262–70. 

Paragraph 6 of 35 U.S.C. § 112 allows “[a]n element in a 

claim for a combination” to “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.” Pursuant to 35 U.S.C. 

§ 112, ¶ 6, if the specification of a patent does not disclose 

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6 ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 

“corresponding structure, material, or acts” for “performing the specified function” in the claims, the patent will be 

found to be invalid for indefiniteness under 35 U.S.C. 

§ 112, ¶ 2 because it does not “distinctly claim[] the 

subject matter . . . the inventor . . . regards as the invention.” 35 U.S.C. § 112, ¶ 2. 

On November 21, 2014, the district court issued the 

decision in dispute. See J.A. 2–37 (District Court’s 

Markman Order). In addition to construing various 

claims of the patents-in-suit, the district court found that 

the terms “symbol generator” and “CPU software” in the 

asserted claims––i.e., claims 3 and 10 of the ’728 patent 

and claims 5 and 9 of the ’681 patent––invoked 35 U.S.C. 

§ 112, ¶ 6, and were indefinite under 35 U.S.C. § 112, ¶ 2. 

See J.A. 9–20. In view of the district court’s decision as to 

indefiniteness, the parties stipulated that these claims 

were invalid. See J.A. 857. 

AGIS appeals the district court’s indefiniteness determinations. This court has jurisdiction over this appeal 

under 28 U.S.C. § 1295(a)(1) (2012). 

DISCUSSION 

Our analysis proceeds in two steps. First, we address 

whether “symbol generator” in the asserted claims is in 

means-plus-function form pursuant to 35 U.S.C. § 112, 

¶ 6. See Robert Bosch, LLC v. Snap–On Inc., 769 F.3d 

1094, 1097 (Fed. Cir. 2014). If we find that the relevant 

claim terms recite a means-plus-function limitation, we 

proceed to our second inquiry and “attempt to construe 

the disputed claim term by identifying the corresponding 

structure, material, or acts described in the specification 

to which the term will be limited.” Id. (internal quotation 

marks and citation omitted); see also O.I. Corp. v. Tekmar 

Co., 115 F.3d 1576, 1583 (Fed. Cir. 1997) (“The price that 

must be paid for use of [a means-plus-function claim] is 

limitation of the claim to the means specified in the 

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written description and equivalents thereof.”). However, 

“[i]f the specification is not clear as to the structure that 

the patentee intends to correspond to the claimed function, then the patentee has not paid that price but is . . . 

attempting to claim in functional terms unbounded by 

any reference to structure in the specification.” Med. 

Instrumentation & Diagnostics Corp. v. Elekta AB, 344 

F.3d 1205, 1211 (Fed. Cir. 2003). We address each step in 

turn.

I. The Claim Term “Symbol Generator” Invokes 35 U.S.C.

§ 112, ¶ 6

The district court held that “symbol generator” and 

“CPU software” in claims 3 and 10 of the ’728 patent and 

claims 5 and 9 of the ’681 patent invoked 35 U.S.C. § 112, 

¶ 6, but were indefinite under 35 U.S.C. § 112, ¶ 2. 

“Symbol generator” appears in all of the asserted claims. 

Thus, if we find that claim term indefinite under 35 

U.S.C. § 112, ¶ 2, we need not independently address 

whether the claim term “CPU software” also renders clam 

10 of the ’728 patent and claim 9 of the ’681 patent invalid 

for indefiniteness.

The district court’s construction of patent claims 

based on evidence intrinsic to the patent, including any 

finding that the claim language invokes 35 U.S.C. § 112, 

¶ 6, is reviewed de novo as a question of law. See Williamson v. Citrix Online, LLC, 792 F.3d 1339, 1346 (Fed. 

Cir. 2015) (en banc) (citation omitted). In construing 

patent claims, if the district court makes underlying 

findings of fact based on extrinsic evidence, such findings 

are reviewed for clear error. Id. “Clear error only exists if 

we are left with a definite and firm conviction that a 

mistake has been committed.” Venture Indus. Corp. v. 

Autoliv ASP, Inc., 457 F.3d 1322, 1331 (Fed. Cir. 2006)

(internal quotation marks and citation omitted). 

If a claim element “contains the word ‘means’ and recites a function,” this creates a presumption that the 

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8 ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 

claim is in means-plus-function form under 35 U.S.C. 

§ 112, ¶ 6. Envirco Corp. v. Clestra Cleanroom, Inc., 209 

F.3d 1360, 1364 (Fed. Cir. 2000) (citation omitted). “That 

presumption falls, however, if the claim itself recites 

sufficient structure to perform the claimed function.” Id. 

(citation omitted). 

“[T]he failure to use the word ‘means’ also creates a 

rebuttable presumption—this time that § 112, para. 6 

does not apply.” Williamson, 792 F.3d at 1348 (citation 

omitted). However, “if the challenger demonstrates that 

the claim term fails to recite sufficiently definite structure 

or else recites function without reciting sufficient structure for performing that function,” this presumption may 

be rebutted. Id. (internal quotation marks, brackets, and 

citation omitted). “The standard is whether the words of 

the claim are understood by persons of ordinary skill in 

the art to have a sufficiently definite meaning as the 

name for structure.” Id. at 1349. In determining whether 

this presumption has been rebutted, the challenger must 

establish by a preponderance of the evidence that the 

claims are to be governed by § 112, ¶ 6. See Apex Inc. v. 

Raritan Comput. Inc., 325 F.3d 1364, 1372 (Fed. Cir. 

2003). 

Here, although the asserted claims do not include the 

word “means,” the district court determined that AGIS 

intended to invoke § 112, ¶ 6. See J.A. 10–11; see also

’728 patent col. 12 l. 52–col. 13 l. 13 (claim 3), col. 14 ll. 

27–61 (claim 10); ’681 patent col. 12 l. 52–col. 13 l. 18 

(claim 5), col. 13 l. 44–col. 14 l. 27 (claim 9). According to 

the district court, “[a] plain reading of the term in context 

of the relevant claim language suggests the term ‘symbol 

generator’ is analogous to a ‘means for generating symbols’ because the term is simply a description of the 

function performed.” J.A. 10–11 (citation omitted). The 

district court also determined “the term is not used in 

common parlance or by persons of ordinary skill in the 

pertinent art to designate structure.” J.A. 11 (internal 

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quotation marks and citation omitted). Finally, the 

district court rejected the testimony of AGIS’s expert, Dr. 

Benjamin Goldberg, because he was “not aware whether 

the term symbol generator has a meaning in computer 

science.” J.A. 11 (internal quotation marks and citation

omitted). 

AGIS challenges the district court’s determination, 

asserting that the district court “erred when it concluded 

that the ‘symbol generator’ elements in [the asserted 

claims] are subject to § 112, ¶ 6.” AGIS’s Br. 25. Specifically, AGIS avers that Life360 failed to present sufficient 

evidence demonstrating that “symbol generator” invokes 

§ 112, ¶ 6. See id. at 26, 32. According to AGIS, “[t]he 

unrebutted expert evidence [of Dr. Goldberg] . . . showed 

that persons of ordinary skill would have understood the 

claimed symbol generator to have a sufficiently definite 

meaning as the name for structure.” Id. at 26–27 (internal quotation marks and citation omitted); see also id. at 

27 (stating that “Dr. Goldberg testified that those skilled 

in the art would have understood a ‘symbol generator’ to 

refer to a well-known class of existing, available, standard 

modules of software code used to generate symbols on a 

display” (citations omitted)). 

The term “symbol generator” invokes the application 

of § 112, ¶ 6 because it fails to describe a sufficient structure and otherwise recites abstract elements “for” causing 

actions, ’728 patent col. 14 ll. 45–47, or elements “that 

can” perform functions, ’681 patent col. 12 l. 62. Through 

the testimony of Dr. Goldberg, AGIS contends “those 

skilled in the art would have understood a ‘symbol generator’ to refer to a class of structures instead of a particular 

structure.” AGIS’s Br. 27; see also id. at 28 (stating that 

“Dr. Goldberg’s unrebutted testimony that those skilled in 

the art would have understood what a ‘symbol generator’ 

is, and would have known how to select and use one from 

the well-known class of software modules, demonstrates 

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that the words have a sufficiently definite meaning as the 

name for structure” (internal quotation marks and citation omitted)). However, contrary to AGIS’s contention, 

Dr. Goldberg testified that the term “symbol generator” is 

a term coined for the purposes of the patents-in-suit. See 

J.A. 798. The term is not used in “common parlance or by 

persons of skill in the pertinent art to designate structure,” such that it connotes sufficient structure to avoid 

the application of 35 U.S.C. § 112, ¶ 6. Lighting World, 

Inc. v. Birchwood Lighting, Inc., 382 F.3d 1354, 1359 

(Fed. Cir. 2004), overruled on other grounds by Williamson, 792 F.3d at 1348–49. 

We see no clear error in the district court’s findings 

regarding Dr. Goldberg’s testimony. Dr. Goldberg’s 

testimony that the terms “symbol” and “generator” are 

known within the field of computer science is not dispositive and does not require us to find that 35 U.S.C. § 112, 

¶ 6 does not apply. See J.A. 11 (stating that “Dr. Goldberg testified he was aware of the terms ‘symbol’ and 

‘generator’ separately, but was unaware of [the] use [of] 

the specific term ‘symbol generator’ within the field of 

computer science” (citation omitted)). Irrespective of 

whether the terms “symbol” and “generator” are terms of 

art in computer science, the combination of the terms as 

used in the context of the relevant claim language suggests that it is simply an abstraction that describes the 

function being performed (i.e., the generation of symbols). 

See, e.g., ’728 patent col. 3 ll. 44–46 (“Each cellular 

phone/[Personal Digital Assistant (‘PDA’)/[Global Positioning System (‘GPS’)]” is identified on the display of 

other phone systems by a symbol that is generated to 

indicate its identity.” (emphasis added)); see also ’681 

patent col. 7 ll. 14–17 (“Each cellular phone device is 

identified on the map display of the other participant/user 

cell phone devices by a display symbol that is generated on 

each user cell phone device display to indicate each user’s 

identity.” (emphasis added)). 

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Finally, the claim term “symbol generator,” by itself, 

does not identify a structure by its function, cf. Personalized Media Commc’ns v. ITC, 161 F.3d 696, 705 (Fed. Cir. 

1998) (stating that the claim term “digital detector” does 

not invoke § 112, ¶ 6 because “[e]ven though the term 

‘detector’ does not specifically evoke a particular structure, it does convey to one knowledgeable in the art a 

variety of structures known as ‘detectors’”), nor do the 

asserted claims suggest that the term “symbol generator” 

connotes a definite structure, see Media Rights Techs., 

Inc. v. Capital One Fin. Corp., 800 F.3d 1366, 1372 (Fed. 

Cir. 2015) (finding that the term “compliance mechanism” 

invokes § 112, ¶ 6, because the asserted claims “simply 

state that the ‘compliance mechanism’ can perform various functions” (emphasis added)). Accordingly, because 

the term “symbol generator” does not describe anything 

structural, the district court was correct to conclude that 

the asserted claims which recite the term “symbol generator” are subject to 35 U.S.C. § 112, ¶ 6. 

II. The Claim Term “Symbol Generator” Is Indefinite 

Under § 112, ¶ 2

Because the claim term “symbol generator” is a 

means-plus-function term as described by paragraph 6 of 

§ 112, we must “construe the disputed claim term by 

identifying the corresponding structure, material, or acts 

described in the specification to which the claim term will 

be limited.” Robert Bosch, 769 F.3d at 1097 (internal 

quotation marks and citation omitted). If a patentee 

“employs means-plus-function language in a claim, [the 

patentee] must set forth in the specification an adequate 

disclosure showing what is meant by that language.” 

Blackboard, Inc. v. Desire2Learn, Inc., 574 F.3d 1371, 

1382 (Fed. Cir. 2009) (internal quotation marks and 

citation omitted). “If the specification does not contain an 

adequate disclosure of the structure that corresponds to 

the claimed function, the patentee will have failed to 

particularly point out and distinctly claim the invention 

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12 ADVANCED GROUND INFO. SYS., INC. v. LIFE360, INC. 

[under § 112, ¶ 2], which renders the claim invalid for 

indefiniteness.” Id. (internal quotation marks and citation omitted). 

We agree with the district court’s determination that 

the “term ‘symbol generator’ is indefinite.” J.A. 13 (footnote omitted). Although the district court recognized that 

“the specification [] describe[s], in general terms, that 

symbols are generated based on the latitude and longitude of the participants,” it nonetheless determined that 

the specification “fails to [disclose] an ‘algorithm’ or 

description as to how those symbols are actually ‘generated.’” J.A. 12 (citation omitted). 

“[I]n a means-plus-function claim in which the disclosed structure is a computer[] or microprocessor[] programmed to carry out an algorithm, [as is the case here], 

the disclosed structure is . . . [a] special purpose computer programmed to perform the disclosed algorithm.” 

Aristocrat Techs. Austl. Pty Ltd. v. Int’l Game Tech., 521 

F.3d 1328, 1333 (Fed. Cir. 2008) (internal quotation 

marks and citation omitted); see ’728 patent col. 3 ll. 57–

61 (stating that “[w]hen the cellular phone/PDA/GPS 

System user uses his stylus or finger to touch one or more 

of the symbols or a location on the cellular phone display, 

the system’s software causes the status and latitude and 

longitude information concerning that symbol or location 

to be displayed”). In the case of computer-implemented 

functions, we require that the specification “disclose an 

algorithm for performing the claimed function.” See Net 

MoneyIN, Inc. v. VeriSign, Inc., 545 F.3d 1359, 1367 (Fed. 

Cir. 2008). The specification can express the algorithm 

“in any understandable terms including as a mathematical formula, in prose, . . . as a flow chart, or in any other 

manner that provides sufficient structure.” Finisar Corp. 

v. DirecTV Grp., Inc., 523 F.3d 1323, 1340 (Fed. Cir. 2008) 

(citation omitted). 

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The specifications of the patents-in-suit do not disclose an operative algorithm for the claim elements reciting “symbol generator.” The function of generating 

symbols must be performed by some component of the 

patents-in-suit; however, the patents-in-suit do not describe this component. Although the specification of the 

’728 patent suggests that these symbols are generated via 

“a map database and a database of geographically referenced fixed locations . . . with a specified latitude and 

longitude[,] . . . [and] [a] database with the constantly 

updated GPS location,”’ 728 patent col. 3 ll. 35–41, this 

only addresses the medium through which the symbols 

are generated. A patentee cannot claim a means for 

performing a specific function and subsequently disclose a 

“general purpose computer as the structure designed to 

perform that function” because this “amounts to pure 

functional claiming.” Aristocrat Techs., 521 F.3d at 1333. 

Accordingly, because the specifications of the patents-insuit do not disclose sufficient structure for the “symbol 

generator” function and the asserted claims include this 

term, the asserted claims are indefinite under 35 U.S.C. § 

112, ¶ 2. 

CONCLUSION

For the foregoing reasons, the decision of the United 

States District Court for the Southern District of Florida 

is

AFFIRMED

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