Case: 20-1718 Document: 47 Page: 1 Filed: 07/13/2021
NOTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
LEVEL SLEEP LLC,
Plaintiff-Appellant
v.
SLEEP NUMBER CORPORATION, SELECT
COMFORT RETAIL CORPORATION,
Defendants-Appellees
______________________
2020-1718
______________________
Appeal from the United States District Court for the
Eastern District of Texas in No. 2:18-cv-00119-RWS, Judge
Robert Schroeder, III.
______________________
Decided: July 13, 2021
______________________
JAMES L. DAY, JR., Farella Braun & Martel LLP, San
Francisco, CA, argued for plaintiff-appellant. Also repre-
sented by LAURA PEDERSEN.
RUFFIN B. CORDELL, Fish & Richardson P.C., Washing-
ton, DC, argued for defendants-appellees. Also repre-
sented by ROBERT COURTNEY, CONRAD GOSEN, MATHIAS
WETZSTEIN SAMUEL, Minneapolis, MN.
______________________
Case: 20-1718 Document: 47 Page: 2 Filed: 07/13/2021
2 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
Before O’MALLEY, TARANTO, and STOLL, Circuit Judges.
STOLL, Circuit Judge.
Level Sleep LLC appeals the United States District
Court for the Eastern District of Texas’s grant of summary
judgment of noninfringement of Level Sleep’s U.S. Patent
Nos. 6,807,698 and 7,036,172. Because we agree with the
district court’s construction of “low body pressure,” and the
parties agree that the accused products do not infringe un-
der that construction, we affirm.
BACKGROUND
I
Level Sleep sued Sleep Number Corporation and Select
Comfort Retail Corporation (collectively, “Sleep Number”)
for infringement of all claims of the ’698 and ’172 patents
(collectively, the “asserted patents”) in March 2018. The
’172 patent is a continuation-in-part of the ’698 patent. 1
The asserted patents relate to “improved mattresses for
beds that enhance the quality of sleep.” ’172 patent col. 1
ll. 10–12. The specification explains that “[g]ood sleeping
is normally associated with a low number of body shifts
during the sleep period[,]” and “[b]ed-induced shifts due to
discomfort caused by the bed are a significant cause of poor
sleep quality.” Id. at col. 1 ll. 37–40. There are two major
causes of bed-induced shifting: (1) “buildup of pressures on
parts of the body”; and (2) “poor body alignment.” Id.
at col. 1 ll. 49–52. Only the first cause relates to the claim
construction issue in this case.
Addressing the buildup of pressures on parts of the
body, the specification explains that “the pressure tends to
be greatest on the body’s protrusions (such as shoulders
1 Because the parties cite to the ’172 patent when
referencing the specification, we do the same.
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LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION 3
and hips) where body tissues are put in high compression
against the mattress.” Id. at col. 1 ll. 54–58. The feeling of
discomfort is in part a result of this high compression caus-
ing a discontinuance of capillary blood flow. The specifica-
tion states that “[t]he amount of pressure [that] causes a
discontinuance of capillary blood flow is called the ischemic
pressure[,]” and the “ischemic pressure threshold is nor-
mally considered to be approximately thirty mmHg.” Id.
at col. 1 ll. 60–63. “When parts of the body (usually shoul-
ders and hips in conventional mattresses) are subjected to
pressures above the ischemic threshold, discomfort results”
and the person generally shifts to relieve the pressure. Id.
at col. 1 l. 66–col. 2 l. 3.
To reduce these high pressures, the asserted patents
contemplate a mattress that “is capable of supporting a re-
clining body . . . where the reclining body is supported by
low body pressure.” Id. at col. 9 ll. 29–31. The specification
states: “The terminology low body pressure means a pres-
sure which is below a pressure threshold (typically the is-
chemic threshold) for comfortable sleep and of a level which
materially reduces causes of bed-induced shifting.” Id.
at col. 9 ll. 32–35.
Figure 10 illustrates a side view of a conventional mat-
tress with the resultant surface body pressures:
Id. Fig. 10. The specification explains that “the surface
pressures T’1, T’2, T’3 and T’4 at the shoulder alignment line
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4 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
1710-1, the waist alignment line 1710-2, the hip alignment
line 1710-3 and the leg alignment line 1710-4 are typically
80, 40, 80 and 30 mmHg, respectively.” Id. at col. 15
ll. 33–37. The asserted patents explain that the “80 and 40
values are above the ischemic pressure threshold and
hence tend to cause bed-induced shifting in a conventional
mattress.” Id. at col. 15 ll. 37–39.
In comparison, Figure 11 illustrates a side view of an
embodiment of the asserted patents:
Id. Fig. 11. The specification discloses that, in this embod-
iment, “[t]he surface pressures T1, T2, T3 and T4 at the
shoulder alignment line 1711-1, the waist alignment line
1711-2, the hip alignment line 1711-3 and the leg alignment
line 1711-4 are typically low and below a low pressure
threshold.” Id. at col. 16 ll. 19–23. In this preferred em-
bodiment, “the low pressure threshold is below the is-
chemic pressure of about 30 mmHg.” Id. at col. 16
ll. 24–25.
Independent claim 1 of the ’172 patent is illustrative of
the claims on appeal and recites:
1. A mattress, extending in a lateral direction from
side to side and extending in a longitudinal direc-
tion from a mattress head to a mattress foot, for
supporting a reclining body, said mattress includ-
ing a head part, a shoulder part, a waist part, a hip
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LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION 5
part and a leg part, said reclining body having a
displacement profile, said mattress comprising,
a core extending in said longitudinal direction and
in said lateral direction, said core for undergoing
differing vertical displacements when supporting
the reclining body,
said core having displacement parameters varying
to match the displacement profile of the reclining
body whereby the reclining body is supported by low
body pressure,
said core having a plurality of regions where the
vertical displacement in one or more of the regions
varies to match the displacement profile of the re-
clining body to maintain the reclining body in
alignment,
said core including one or more foam members hav-
ing structural modification where the one or more
foam members at different longitudinal positions
exhibit different displacement parameters includ-
ing different ILDs to support the reclining body
with low body pressure and exhibits different verti-
cal displacements to maintain the reclining body in
alignment.
Id. at col. 39 ll. 24–48 (emphases added to disputed limita-
tions).
Because Level Sleep relies on dependent claims 11 and
12 of the ’172 patent and the doctrine of claim differentia-
tion to support its construction of “low body pressure,” we
introduce these claims as well. Dependent claims 11 and
12 of the ’172 patent ultimately depend from claim 1 and
further define the features of the claimed mattress:
11. The mattress as in claim 3 wherein said low
body pressure is below a low pressure threshold.
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6 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
12. The mattress as in claim 11 wherein said
threshold is below an ischemic pressure threshold.
Id. at col. 40 ll. 44–47.
II
At the Markman hearing, the parties agreed that the
term “low body pressure” as recited in the ’172 patent and
“low supporting surface pressure” as recited in the ’698 pa-
tent (the “low pressure” limitations) should be construed
consistently across both patents. Level Sleep asserted that
the “low pressure” limitations should be construed to mean
a “[l]ower surface pressure supporting the body as com-
pared to conventional mattresses,” while Sleep Number as-
serted that they should be construed to mean “pressure
below about 30 mmHg.” Level Sleep LLC v. Sleep No.
Corp., No. 2:18-cv-00119, 2019 WL 2221601, at *4 (E.D.
Tex. May 22, 2019) (Claim Construction Order). The dis-
trict court construed the “low pressure” limitations to mean
“pressure of a level which materially reduces causes of bed-
induced shifting.” Id. at *7 (emphasis omitted).
Subsequently, in opposing Sleep Number’s motion for
summary judgment of noninfringement, Level Sleep sub-
mitted the expert report of Dr. Elizabeth Friis, who tested
the accused mattresses and compared the claim limitations
to the accused mattresses. As part of her testing, Dr. Friis
compared (1) the average surface pressure, (2) the percent
of pressure readings above 30 mmHg, and (3) the maxi-
mum measured surface pressure of each accused mattress
to that of a conventional mattress. Dr. Friis determined
that the accused products outperformed the conventional
mattress in each of these measured categories, generally
resulting in lower surface pressures as compared to the
conventional mattress. As such, Dr. Friis concluded that
each of the accused products met the “low pressure” limita-
tions as construed by the district court to mean “pressure
of a level which materially reduces causes of bed-induced
shifting.” J.A. 4664. Dr. Friis’s testing also demonstrated,
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LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION 7
however, that the maximum measured surface pressure of
each of the accused products was above 40 mmHg. See, e.g.,
J.A. 4777. In at least some of the testing, the accused prod-
ucts exhibited pressures below 80 mmHg at the shoulder
and below 40 mmHg at the waist. See, e.g., J.A. 4810.
In January 2020, the district court granted summary
judgment of noninfringement of both patents. Order at 1,
Level Sleep LLC v. Sleep No. Corp., No. 2:18-cv-00119 (E.D.
Tex. Jan. 14, 2020), ECF No. 178 (Summary Judgment Or-
der). The district court explained that although it previ-
ously construed the “low pressure” limitations as “pressure
of a level which materially reduces causes of bed-induced
shifting,” it had “instructed that any testimony relating to
the Court’s construction must be ‘constrained by the
Court’s reasoning.’” Id. at 5 (quoting Claim Construction
Order, 2019 WL 2221601, at *15). The district court ex-
plained that while it rejected Sleep Number’s proposed up-
per limit of 30 mmHg, it recognized that the “low pressure”
limitations must have some upper limit. Summary Judg-
ment Order at 5–6. The district court reasoned that alt-
hough the intrinsic evidence does not “establish a specific
bright-line level,” the specification criticizes prior-art mat-
tresses with pressures of 40 mmHg and thus makes clear
that pressures of 40 mmHg are too high to satisfy the “low
pressure” limitations. Id. at 6 (internal quotation marks
omitted). The district court subsequently rejected Level
Sleep’s alternative argument that, if there is an upper
limit, it is 80 mmHg at the shoulder and hip and 40 mmHg
at the waist. Id. Considering the evidence presented—
namely, Dr. Friis’s expert report—the district court con-
cluded that there was no genuine dispute that the accused
products had a maximum pressure above 40 mmHg and,
accordingly, the accused products could not as a matter of
law infringe the claims as properly construed. Id. at 8–9.
Level Sleep appeals. We have jurisdiction pursuant to
28 U.S.C. § 1295(a)(1).
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8 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
DISCUSSION
I
On appeal, Level Sleep challenges the district court’s
grant of summary judgment on several grounds. First, it
asserts that it introduced substantial, admissible evidence
showing that the accused mattresses meet the claim limi-
tations as construed by the district court in the initial claim
construction order. As part of this argument, it asserts
that the district court erred by sua sponte changing its con-
struction when granting summary judgment. Finally,
Level Sleep challenges the district court’s construction of
the “low pressure” limitations as requiring pressure levels
that are at least lower than 40 mmHg. We review a district
court’s claim construction de novo where, as here, it de-
pends only on the intrinsic evidence. Teva Pharms. USA,
Inc. v. Sandoz, Inc., 574 U.S. 318, 331 (2015); see also Trs.
of Columbia Univ. v. Symantec Corp., 811 F.3d 1359, 1362
(Fed. Cir. 2016) (“The construction of claim terms based on
the claim language, the specification, and the prosecution
history are legal determinations.”).
A
We start by addressing Level Sleep’s assertion that the
district court erred by changing its claim construction sua
sponte in the summary judgment order. This argument
fails because “a district court may (and sometimes must)
revisit, alter, or supplement its claim constructions . . . to
the extent necessary to ensure that final constructions
serve their purpose of genuinely clarifying the scope of
claims for the finder of fact.” In re Papst Licensing Digit.
Camera Pat. Litig., 778 F.3d 1255, 1261 (Fed. Cir. 2015)
(first citing O2 Micro Int’l Ltd. v. Beyond Innovation Tech.
Co., 521 F.3d 1351, 1359 (Fed. Cir. 2008); and then citing
Pfizer, Inc. v. Teva Pharm., USA, Inc., 429 F.3d 1364, 1377
(Fed. Cir. 2005)). Indeed, we have held that district courts
“may engage in a rolling claim construction, in which the
court revisits and alters its interpretation of the claim
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LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION 9
terms as its understanding of the technology evolves.”
Jack Guttman, Inc. v. Kopykake Enters., Inc., 302 F.3d
1352, 1361 (Fed. Cir. 2002). And we have explained that
“a district court may engage in claim construction during
various phases of litigation, not just in a Markman order.”
Conoco, Inc. v. Energy & Envt’l Int’l, L.C., 460 F.3d 1349,
1359 (Fed. Cir. 2006). Under our precedent, the district
court was well within its power to clarify, supplement, and
even alter its construction of the “low pressure” limitations
in its summary judgment order. 2
B
We next turn to whether the district court’s modified
claim construction—requiring “low pressure” to be at least
below 40 mmHg—is proper in light of the intrinsic evi-
dence. We determine that it is.
Illustrative claim 1 of the ’172 patent recites a mattress
comprising a core having features “whereby the reclining
body is supported by low body pressure.” ’172 patent
col. 39 ll. 37–38. While the claim language itself is not par-
ticularly helpful in understanding the meaning of “low
body pressure,” the patent specification expressly defines
the term. It states: “The terminology low body pressure
means a pressure which is below a pressure threshold (typ-
ically the ischemic threshold) for comfortable sleep and of
a level which materially reduces causes of bed-induced
2 While our decision does not rely on it, we further
note that we do not necessarily agree with Level Sleep that
the district court wholly changed its construction. As the
district court itself explained, though it “declined to adopt
Sleep Number’s proposed upper limit of 30 mmHg” in its
Markman order, it “agreed with and adopted [Sleep Num-
ber’s] argument that the patents disclosed pressure levels
(40 and 80 mmHg) that the patents ‘considered too high.’”
Summary Judgment Order, at 5–6.
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10 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
shifting.” Id. at col. 9 ll. 32–35. The specification further
discloses that the surface pressures at the shoulder, waist,
hip, and leg alignment lines “are typically low and below a
low pressure threshold.” Id. at col. 16 ll. 19–23. It adds
that this “low pressure threshold is below the ischemic
pressure of about 30 mmHg.” Id. at col. 16 ll. 24–25. We
have previously explained that where “a patent applicant
has elected to be a lexicographer by providing an explicit
definition in the specification for a claim term[,]” the “defi-
nition selected by the applicant controls.” Renishaw PLC
v. Marposs Societa’ Per Azioni, 158 F.3d 1243, 1249
(Fed. Cir. 1998).
In addition, the specification disavows a “low pressure”
of 40 mmHg or above by characterizing pressure levels of
40 mmHg as not achieving the required reduction of bed-
induced shifting. “Disavowal requires that the specifica-
tion [] make[] clear that the invention does not include a
particular feature, . . . or is clearly limited to a particular
form of the invention[.]” Hill-Rom Servs., Inc. v. Stryker
Corp., 755 F.3d 1367, 1372 (Fed. Cir. 2014) (second altera-
tion in original) (internal citations omitted). We have
found disavowal or disclaimer when the patent repeatedly
disparaged an embodiment as “antiquated” and then de-
tailed the “deficiencies [that] make it difficult” to use. Chi-
cago Bd. Options Exch., Inc. v. Int’l Sec. Exch., LLC,
677 F.3d 1361, 1372 (Fed. Cir. 2012) (alteration in origi-
nal). Here, the specification repeatedly disparages “con-
ventional mattresses” as causing shifting in bed due to
discomfort. See ’172 patent, col. 1 ll. 40–44 (“On conven-
tional mattresses . . . most people experience about forty
major postural body shifts [per night.]”); col. 1 l. 66–col. 2
l. 3 (“When parts of the body (usually shoulders and hips in
conventional mattresses) are subjected to pressures above
the ischemic threshold, discomfort results[.]”); col. 3 ll.
25–27 (“Conventional . . . mattresses . . . are generally un-
able to provide the qualities necessary for an ideal mat-
tress.”). The specification then explains that one of the
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LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION 11
reasons discomfort results is that certain surface pressures
of a conventional mattress—including 80 and 40 mmHg—
are above the ischemic pressure threshold. Particularly,
the specification explains that “the surface pressures T’1,
T’2, T’3 and T’4 [of a conventional mattress] at the shoulder
alignment line 1710-1, the waist alignment line 1710-2, the
hip alignment line 1710-3 and the leg alignment line 1710-4
are typically 80, 40, 80 and 30 mmHg, respectively.” Id.
at col. 15 ll. 30–37. It continues by explaining that these
“80 and 40 values are above the ischemic pressure thresh-
old and hence tend to cause bed-induced shifting in a con-
ventional mattress.” Id. at col. 15 ll. 37–39.
In our view, the specification limits “low body pressure”
beyond simply “a level which materially reduces causes of
bed-induced shifting.” Id. at col. 9 ll. 32–35. The express
definition of “low body pressure” includes this phrase, but
it also states that “low body pressure means a pressure
which is below a pressure threshold (typically the ischemic
threshold)[,]” id., and the specification disparages surface
pressures of 40 mmHg or above as being “above the is-
chemic pressure threshold and hence tend[ing] to cause
bed-induced shifting in a conventional mattress[,]” id.
at col. 15 ll. 37–39. Accordingly, we agree with the district
court’s construction that “low body pressure” is a pressure
falling below a pressure threshold that materially reduces
causes of bed-induced shifting and, whatever that specific
threshold is, it is lower than 40 mmHg.
Level Sleep’s reliance on claim differentiation based on
dependent claims 11 and 12 is unavailing. Though these
claims purport to narrow the independent claim by requir-
ing a “low pressure threshold,” and that the “threshold is
below an ischemic pressure threshold,” id. at col. 40
ll. 44–47, at most, they support Level Sleep’s successful ar-
gument to the district court that the “low body pressure”
limitation in claim 1 is not 30mmHg. Because the doctrine
of claim differentiation “does not serve to broaden claims
beyond their meaning in light of the specification,” Intell.
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12 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
Ventures I v. Motorola Mobility LLC, 870 F.3d 1320, 1326
(Fed. Cir. 2017) (quoting Toro Co. v. White Consol. Indus.,
Inc., 199 F.3d 1295, 1302 (Fed. Cir. 1999)), the dependent
claims cannot erase express definitions and disclaimers in
the patent specification. Here, the specification is clear:
“low body pressure means a pressure which is below a pres-
sure threshold.” ’172 patent col. 9 ll. 32–33. Furthermore,
pressures of 40 mmHg “tend to cause bed induced shifting
in a conventional mattress.” Id. at col. 15 ll. 37–39.
Level Sleep alternatively asserts that if a numeric
standard is necessary to construe the “low pressure” limi-
tations, then the correct standard would be 80 mmHg at
the shoulder, 40 mmHg at the waist, and 80 mmHg at the
hip. We disagree. Nothing in the patent specification sug-
gests to a person of ordinary skill in the art to differentiate
pressure thresholds between different parts of the body. To
the contrary, in the background of the invention section,
the specification explains that “[w]hen parts of the body
(usually shoulders and hips in conventional mattresses)
are subjected to pressures above the ischemic threshold
[i.e., 30 mmHg], discomfort results” and the person gener-
ally shifts to relieve the pressure. Id. at col. 1 l. 66–col. 2
l. 3 (emphasis added). Similarly, in disclosing various sur-
face pressures from a conventional mattress at the shoul-
der, waist, and hip alignment lines, the specification
explains that the “80 and 40 values are above the ischemic
pressure threshold and hence tend to cause bed-induced
shifting in a conventional mattress.” Id. at col. 15 ll. 37–39.
In both of these examples, the specification expressly con-
templates the surface pressure that would result in discom-
fort at various parts of the body, and in both cases the
specification recognizes just a single pressure threshold for
causing discomfort at those various parts.
This comports with the embodiments contemplated by
the asserted patents. In Figure 11, the specification dis-
closes surface pressures at each of the shoulder, waist, hip,
and leg alignment lines. Id. at col. 16 ll. 19–23; Fig. 11.
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LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION 13
There, it explains that the surface pressures at these align-
ment lines “are typically low and below a low pressure
threshold,” where that “low pressure threshold is below the
ischemic pressure of about 30 mmHg.” Id. at col. 16
ll. 19–25. Once again, the specification discloses only a sin-
gle pressure threshold for each of the various parts of the
body. Accordingly, we are not convinced that the specifica-
tion supports Level Sleep’s argument that the claim con-
struction of “low body pressure” should vary based on
different parts of the body. While we appreciate that the
claims and the specification could have defined “low body
pressure” to be different at the hips and shoulders com-
pared to the waist, they did not do so. We thus conclude
that the district court’s construction is most consistent
with the claim language and the specification and we adopt
it as our own.
II
We review a grant of summary judgment according to
the law of the regional circuit, which in this case is the
Fifth Circuit. Ineos USA LLC v. Berry Plastics Corp.,
783 F.3d 865, 868 (Fed. Cir. 2015). The Fifth Circuit re-
views a district court’s grant of summary judgment de
novo. Triple Tee Golf, Inc. v. Nike, Inc., 485 F.3d 253, 261
(5th Cir. 2007). Summary judgment is improper where
there is a genuine dispute of material fact and where “the
evidence is such that a reasonable jury could return a ver-
dict for the nonmoving party.” Anderson v. Liberty Lobby,
Inc., 477 U.S. 242, 248 (1986). In the present case, Sleep
Number asserts that it is undisputed that each of the ac-
cused products exhibits pressure exceeding 40 mmHg.
Thus, if we agree with the district court’s construction, no
genuine issue of material fact exists. Level Sleep concedes
this point. Oral Arg. at 17:53–18:33, http://oralargu-
ments.cafc.uscourts.gov/default.aspx?fl=20-
1718_01052021.mp3 (“I don’t believe that the record evi-
dence and the infringement contentions we made based on
the original construction provide a basis to change the
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14 LEVEL SLEEP LLC v. SLEEP NUMBER CORPORATION
[district court’s summary judgment] decision if forty is an
upper limit.”). Because we determine that the correct
claim construction recognizes pressures above 40 mmHg as
too high to meet the “low pressure” limitations, there is no
dispute of material fact in this case that would preclude
summary judgment of noninfringement.
CONCLUSION
We have considered Level Sleep’s remaining argu-
ments and find them unpersuasive. For the foregoing rea-
sons, we affirm the district court’s grant of summary
judgment of noninfringement.
AFFIRMED