Piggy Pushers, LLC v. Skidders Footwear, Inc.

N OTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
PIGGY PUSHERS, LLC,
Plaintiff-Appellant,
v.
SKIDDERS FOOTWEAR, INC.,
Defendant-Appellee.
______________________
2013-1107
______________________
Appeal from the United States District Court for the
Western District of Michigan in No. 10-CV-0644, Judge
Robert Holmes Bell.
______________________
Decided: November 8, 2013
______________________
CASEY L. G RIFFITH , Klemchuk Kubasta, LLP, of Dal-
las, Texas, for plaintiff-appellant. With her on the brief
was K ELSEY W. J OHNSON.
MORRIS E. COHEN, Goldberg Cohen, LLP, of New
York, New York, for defendant-appellee. With him on the
brief was L EE A. G OLDBERG. Of counsel was D AVID B.
SUNSHINE, Cozen O’Connor, of New York, New York.
______________________

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 2
Before WALLACH , L INN, and T ARANTO, Circuit Judges.
P ER CURIAM .
Piggy Pushers, LLC, sued Skidders Footwear, Inc., in
the Western District of Michigan for patent infringement.
After construing the asserted claims and granting sum-
mary judgment of noninfringement, the district court
entered final judgment in favor of Skidders. Piggy Push-
ers appeals. For the reasons set forth below, we affirm.
BACKGROUND
Piggy Pushers owns U.S. Patent No. 6,385,779, which
is directed to infant socks with “gripper” surfaces that
provide traction for crawling and walking. Each claimed
sock is infant-sized and includes a gripper—a friction-
enhancing material, such as rubber—covering at least a
portion of the upper, lower, and toe surfaces of the sock.
’779 patent, col. 1, lines 52-67; id., col. 4, lines 13-28. The
placement of the gripper surface allows it to touch the
floor whether the infant is crawling (when part of the top
of the foot, or the toes, touch the floor) or walking (when
the bottom of the foot touches the floor), thus distinguish-
ing prior-art socks that allegedly provided traction only on
the bottom of the sock. Id., col. 1, lines 26-48. Claim 1 is
representative:
1. An infant sock for crawling infants comprising:
a sock member sized to fit a foot of an infant
learning to crawl, said sock member having an
exterior upper surface and an exterior lower
surface extending between an open end and a
closed end, said closed end having an exterior
toe surface; and
a gripper member connected to said sock member,
said gripper member covering at least a portion
of each of said exterior upper surface, said exte-
rior lower surface and said exterior toe surface,

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 4
makes footwear, including the accused product for twelve-
month-old children, pictured below:
J.A. 352. The product consists of a foot-surrounding sock
bonded to a rubber outsole. Piggy Pushers, LLC v. Skid-
ders Footwear, Inc., No. 1:10-CV-644, 2012 WL 5398801,
at *4 (W.D. Mich. Nov. 2, 2012).
On March 5, 2012, the district court issued its opin-
ion construing various terms of the ’779 patent. Piggy
Pushers, LLC v. Skidders Footwear, Inc., No. 1:10-CV-644,
2012 WL 718907 (W.D. Mich. Mar. 5, 2012). First, the
court construed the preamble of each claim at issue as
limiting the claimed invention as a whole to a “sock.” Id.
at *2-3. As to the meaning of the term “sock,” the court
said that “[n]othing in the claim language or the specifica-

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 5
tions suggests that the inventor intended ‘sock’ to mean
anything other than what a person of ordinary skill in the
art of footwear would understand it to mean.” Id. at *3.
The court then said that it was construing “sock” to mean
“a knitted or woven covering for the foot”—even while
indicating that the ordinary meaning governed to distin-
guish a shoe. Id. The court construed “sock member” to
mean “a part of the sock” and construed “a sock member
sized to fit a foot of an infant learning to crawl” to mean
“a sock member of a size such that it conforms to the foot
of an infant learning to crawl.” Id. at *4-5. Neither party
argued that “gripper member” required construction;
accordingly, the court did not construe that phrase. Id. at
*2.
On August 6, 2012, Skidders moved for summary
judgment of noninfringement, which the district court
granted on November 2, 2012. Piggy Pushers, 2012 WL
5398801, at *1. The district court recited evidence that
the accused product has various qualities consistent with
shoes—such as a thick, durable outsole, a separate insole,
a fixed size and shape, a design not intended to be worn
inside a shoe, and left-foot and right-foot designations—
evidence to which Piggy Pushers “raised few challenges.”
Id. at *2-3. At the same time, the district court noted that
there was “no dispute that the Accused Product consists of
a sock that has been bonded to a rubber outsole”; that
Skidders had described the accused product as “sock-like,”
as a “sock with rubber outsole,” and as a “hybrid sock-
shoe design”; and that “retailers could not decide whether
to put [the accused product] in the hosiery department or
the shoe department.” Id. at *4 (internal quotation marks
omitted).
Considering the evidence presented, the district court
concluded that Piggy Pushers was entitled to summary
judgment of noninfringement. Although Piggy Pushers
had shown “a question of fact as to whether the Accused
Product is a hybrid shoe and sock,” the court reasoned,

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 6
the ’779 patent “addresses a sock,” not “a hybrid sock-
shoe,” and there was “simply no evidence from which a
reasonable jury could conclude that [Skidders’s] product is
a sock.” Id. That conclusion—which appears to have
relied on the ordinary meaning of “sock” in addition to the
“knitted or woven covering for the foot” language of the
claim-construction opinion—sufficed for summary judg-
ment of noninfringement. Id. at *5. As an alternative
basis for granting summary judgment, the district court
agreed with Skidders that “any reasonable jury would
find that because the sock member of the Accused Product
is bonded to a rigid rubber sole, the sock portion of the
Accused Product does not conform to the foot,” as required
by the district court’s construction. Id. at *6 (emphasis
added). For those reasons, the district court entered
judgment in favor of Skidders, a judgment that became
final upon the stipulated dismissal of counterclaims
without prejudice. See Doe v. United States, 513 F.3d
1348, 1353-55 (Fed. Cir. 2008); Hicks v. NLO, Inc., 825
F.2d 118, 120 (6th Cir. 1987).
Piggy Pushers appeals. We have jurisdiction pursu-
ant to 28 U.S.C. § 1295(a)(1).
D ISCUSSION
Piggy Pushers challenges the district court’s construc-
tion of the preambles as limiting the claims, its conclusion
that no reasonable jury could find that the accused prod-
uct is a “sock,” and its conclusion that no reasonable jury
could find that the sock portion of the accused product
conforms to the foot. We review the district court’s claim
construction and its grant of summary judgment de novo.
Cybor Corp. v. FAS Techs., Inc., 138 F.3d 1448, 1451 (Fed.
Cir. 1998); Honeywell Int’l, Inc. v. ITT Indus., Inc., 452
F.3d 1312, 1317 (Fed. Cir. 2006).

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 7
A
Because some preambles are limiting and others not,
we focus on the sole concrete issue at stake in deciding
whether the particular preambles here are limiting—
namely, whether, when the elements recited in the body
of the claims are combined as claimed, the result must
itself be a sock. We think the answer plain from the
specification, which uniformly describes what results from
combining the sock member with the gripper member as
itself remaining a “sock.” ’779 patent, cols. 1 and 2 (back-
ground of the invention; summary of the invention). In
particular, the specification distinguishes a sock from a
“shoe,” which can be undesirable or difficult to put on an
infant; so the addition of the gripper cannot transform the
sock into a shoe. ’779 patent, col. 1, lines 22-25. More
generally, introducing the invention, the specification
explains that “socks can be disadvantageous on smooth
floor surfaces . . . because there is a very low coefficient of
friction between fabric material of the socks and the floor
surface,” id., col. 1, lines 17-20 (emphasis added), and that
the inventors have conceived and described a particular
kind of “sock” that overcomes that problem, without the
use of a “shoe,” and does so for crawling infants, not just
those who can walk, id., col. 1, lines 10-11, 42-49, 52-53,
66; id., col. 2, line 19.
The requirement that the combined elements form a
“sock” is a “fundamental characteristic of the claimed
invention.” Poly-Am., L.P. v. GSE Lining Tech., Inc., 383
F.3d 1303, 1310 (Fed. Cir. 2004) (internal quotation
marks omitted). We therefore affirm the construction of
the preambles as limiting to the extent necessary to
express the idea that the claims each cover a sock, not a
shoe or another article that may be derivative or partly
made up of a sock but is not itself a sock. See Am. Med.
Sys., Inc. v. Biolitec, Inc., 618 F.3d 1354, 1358 (Fed. Cir.
2010) (“Whether to treat a preamble term as a claim
limitation is determined on the facts of each case in light

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 8
of the claim as a whole and the invention described in the
patent.”) (internal quotation marks omitted).
B
That conclusion decides this case, because “[n]o rea-
sonable juror could conclude that the Accused Product is a
sock as defined in the patent.” Piggy Pushers, 2012 WL
5398801, at *5 (emphasis added). Once the preamble
language is accepted as a limitation of the whole product
to a “sock,” Piggy Pushers’s only meaningful argument
about whether the accused product is a “sock” relies on
“sock” having only the meaning of “a knitted or woven
covering for the foot.” But that approach, while under-
standable given some aspects of the district court’s claim-
construction opinion, is not ultimately sensible consider-
ing the full context of the patent and the litigation.
The “knitted or woven covering” formulation is neces-
sarily incomplete. If it meant to exclude all non-knitted
and non-woven components, it could not fit this patent,
which is all about adding such components. Once it is
acknowledged that additions to the knitted or woven
material are allowed, nothing in the “knitted or woven
covering” formulation itself supplies a principle to identify
what additions are allowed. Yet there must be such a
limit, given the undisputed exclusion of shoes—which can
readily include foot coverings made of woven material
such as canvas.
For such reasons, the governing construction of “sock”
must, instead, include its ordinary meaning, captured
centrally but not exclusively by the knitted-or-woven-
covering language. That is evidently how the district
court understood the construction it was applying on
summary judgment: the ultimate product must remain a
“sock” in its ordinary meaning, even with the addition of
friction-enhancing components. Importantly, Piggy
Pushers does not argue here that there was a change of
construction that unfairly denied it the opportunity to

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PIGGY PUSHERS, LLC v. SKIDDERS FOOTWEAR, INC. 9
present evidence—which it plainly did present—on
whether the accused product was covered by the fuller
understanding of “sock” that incorporated the word’s
ordinary meaning.
Under that construction, Piggy Pushers has no chal-
lenge to the summary-judgment ruling. It argues that the
accused product includes a sock, but that is not enough.
It had evidence that Skidders sometimes described the
product as a “sock with rubber outsole,” or in similar
terms, but never simply as a sock. Piggy Pushers, 2012
WL 5398801, at *4 (emphasis added). It had evidence,
too, that “retailers could not decide whether to put [it] in
the hosiery department or the shoe department.” Id. But
such evidence showed at most a hybrid character of the
product. Piggy Pushers had no evidence to respond to
Skidders’s evidence that the product, with its rigid rubber
sole severely constraining flexibility in shape and size,
was not a “sock” under that term’s ordinary meaning,
applied within the context of this patent. Id. at *3-4. In
these circumstances, there is no evidence from which a
jury could reasonably find that the product actually is a
sock.
In light of that conclusion, we need not reach the dis-
trict court’s alternative ground of decision, concerning a
requirement that a covered product conform to the foot.
CONCLUSION
For the reasons stated above, we affirm the district
court’s construction of the asserted claims as limited to
“socks” and the grant of summary judgment based on that
construction.
No costs.
AFFIRMED

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