Metrom Rail, LLC v. Siemens Mobility, Inc., Hitachi Rail Gts USA Inc., Fka Ground Transportation Systems…

N OTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
METROM RAIL, LLC,
Appellant
v.
SIEMENS MOBILITY, INC., HITACHI RAIL GTS
USA INC., FKA GROUND TRANSPORTATION
SYSTEMS USA INC., HUMATICS CORP., PIPER
NETWORKS, INC.,
Cross-Appellants
______________________
2024-2223, 2024-2236, 2024-2264
______________________
Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2023-
00468, IPR2023-00470.
______________________
Decided: May 11, 2026
______________________
G REGORY SCHODDE, McAndrews, Held & Malloy, Ltd.,
Chicago, IL, argued for appellant. Also represented by
RAJENDRA A. CHIPLUNKAR, CHRISTIAN H AVEL HALLERUD,
P HILIPP RUBEN.
MARK MICHAEL SUPKO, Crowell & Moring, LLP, Wash-
ington, DC, argued for all cross-appellants. Also argued by
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 2
HOWARD N. WISNIA, Wisnia PC, San Diego, CA. Cross-ap-
pellant Siemens Mobility, Inc. also represented by J OSHUA
J AMES , Crowell & Moring LLP, Chicago, IL; ALI HOSSEIN
K HAN T EHRANI, Washington, DC.
T HATCHER A. RAHMEIER , Faegre Drinker Biddle &
Reath LLP, Wilmington, DE, for cross-appellant Hitachi
Rail GTS USA Inc. Also represented by L ORA A.
BRZEZYNSKI, Washington, DC.
N ATHAN R. SPEED, Wolf, Greenfield & Sacks, P.C., Bos-
ton, MA, for cross-appellant Humatics Corp.
N ICOLE C UNNINGHAM , Vanguard Crest P.C., Washing-
ton, DC, for cross-appellant Piper Networks, Inc. Also rep-
resented by STEVEN A. MOORE.
______________________
Before D YK, MAYER , and T ARANTO, Circuit Judges.
Opinion for the Court filed by Circuit Judge D YK.
Opinion concurring-in-part and dissenting-in-part
filed by Circuit Judge T ARANTO.
D YK, Circuit Judge.
Siemens Mobility, Inc., Hitachi Rail GTS USA Inc., Hu-
matics Corp., and Piper Networks, Inc. (collectively, “peti-
tioners”) jointly petitioned for inter partes review of U.S.
Patent Nos. 9,043,131 (’131 patent) and 8,812,227 (’227 pa-
tent), both of which are owned by appellant Metrom Rail,
LLC (“Metrom”). The Patent Trial and Appeal Board
(“Board”) instituted review on both patents.
In the final written decisions, the Board determined
that all claims of the ’227 patent and claims 1–16 of the
’131 patent are unpatentable as obvious and that
claims 17–20 of the ’131 patent are not unpatentable as
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 3
obvious over the prior art references cited in the petitions.
Metrom appeals the Board’s unpatentability determina-
tions as to all claims of the ’227 patent and claims 1–16 of
the ’131 patent; the petitioners cross-appeal the Board’s de-
terminations that claims 17–20 of the ’131 patent are not
unpatentable.
With respect to the main appeal, we affirm the Board’s
determination that all of the claims of the ’227 patent and
claims 1–16 of the ’131 patent are unpatentable. As to the
cross-appeal, we reverse the Board’s determination that
claims 17–20 of the ’131 patent are not unpatentable.
BACKGROUND
The ’131 patent and ’227 patent, which are derived
from the same parent application and share a common
specification in all relevant respects, relate to collision-
avoidance systems in the railroad industry. The claimed
collision-avoidance systems in the ’131 and ’227 patents
use sensor technologies such as ultra wideband (“UWB”)
sensing technology and global positioning systems (“GPS”)
to “reliably track the location and speed of vehicles and the
distance between vehicles over a wide variety of track and
terrain.” ’131 patent, abstract.1 Both patents claim a pri-
ority date of May 19, 2011.
Petitioners filed petitions for inter partes review of the
’131 patent and the ’227 patent, arguing all claims were
unpatentable as obvious over multiple proposed prior art
combinations. The primary prior art reference relied on in
both petitions was U.S. Patent No. 6,759,948 (“Grisham”)
(issued July 6, 2004), which petitioners relied on for each
ground of obviousness asserted in both petitions. Grisham
discloses a collision-avoidance system in the railroad in-
dustry using UWB sensing technology. Petitioners relied
1 Unless otherwise noted, we cite to documents in
the ’131 patent inter partes review proceeding.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 4
on Nixon, Int’l Pub. No. WO 03/009254 A1 (“Nixon”) (filed
July 16, 2002) (published Jan. 30, 2003), which also dis-
closes a collision-avoidance system, for the GPS functional-
ity. The Board instituted review on all claims of both
patents.
In the final written decisions, the Board concluded that
each claim of the ’227 patent and claims 1–16 of the
’131 patent are unpatentable as obvious and rejected
Metrom’s contentions that secondary considerations of
nonobviousness established the patentability of the claims,
that certain limitations related to location tracking were
not disclosed in the prior art, and that there was no moti-
vation to combine the prior art references relied on by pe-
titioners. However, the Board determined that
independent claim 17 of the ’131 patent and dependent
claims 18–20 were not unpatentable as obvious because
Grisham did not disclose limitation 17C of claim 17, which
requires “a first wireless communications antenna opera-
ble to send and receive data representing the separation
distance over the air.”
Metrom appeals the Board’s unpatentability determi-
nations as to all the claims of the ’227 patent and claims 1–
16 of the ’131 patent. Petitioners cross-appeal the Board’s
determination that claims 17–20 are not unpatentable as
obvious. We have jurisdiction under 28 U.S.C.
§ 1295(a)(4)(A).
D ISCUSSION
I
The obviousness inquiry is a mixed question of law and
fact. Apple Inc. v. Gesture Tech. Partners, LLC, 127 F.4th
364, 368 (Fed. Cir. 2025). We review the Board’s legal con-
clusion of obviousness de novo and its factual findings re-
lated to obviousness for substantial evidence. Id.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 5
A
We first address the issues raised by the main appeal.
Metrom argues that the Board erred by failing to give
weight to evidence of secondary considerations of nonobvi-
ousness, which it presented in both inter partes review pro-
ceedings. “In order to accord substantial weight to
secondary considerations in an obviousness analysis, the
evidence of secondary considerations must have a nexus to
the claims, i.e., there must be a legally and factually suffi-
cient connection between the evidence and the patented in-
vention.” Fox Factory, Inc. v. SRAM, LLC, 944 F.3d 1366,
1373 (Fed. Cir. 2019) (internal quotations omitted).
“[A] patentee is entitled to a rebuttable presumption of
nexus between the asserted evidence of secondary consid-
erations and a patent claim if the patentee shows that the
asserted evidence is tied to a specific product and that the
product is the invention disclosed and claimed.” Id. (em-
phasis in original) (internal quotations omitted). Metrom
argues that its AURA CAS product, a collision-avoidance
system that uses a combination of UWB sensor technology
and GPS to detect distances between trains and warn op-
erators, is coextensive with the patented inventions and,
therefore, that Metrom was entitled to a presumption of
nexus.
Relying on testimony from Metrom’s CEO, the Board
found that the AURA CAS product had unclaimed “im-
portant features or components,” including “key machine
function monitoring and remote data reporting,” that were
“not insignificant.” J.A. 27–28 (emphasis in original).2
When the product alleged to embody the claims has im-
portant unclaimed features that are not “insignificant” to
2 Citations to the “J.A.” refer to the Joint Appendix
filed by the parties in this case. Dkt. No. 52.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 6
the product, a patentee is not entitled to a presumption of
nexus. Fox Factory, 944 F.3d at 1374–75. We see no error
in the Board’s conclusion that Metrom was not entitled to
a presumption of nexus.
Nexus may also be established by showing that the pro-
posed secondary considerations evidence was the “direct re-
sult of the unique characteristics of the invention.” Id.
at 1373–74 (quoting In re Huang, 100 F.3d 135, 140
(Fed. Cir. 1996)). Metrom failed to make such a showing.
The Board noted that Metrom’s expert, while conclusorily
stating that “the claimed features of the AURA CAS are
the features that drive demand for the AURA CAS,”
J.A. 4195–96, did not “separately identify any unique char-
acteristics” of the patented invention—as embodied in the
AURA CAS product—that drove demand for the AURA
CAS product that were not already known in the prior art,
nor did Metrom “argue that any inventive combination of
known elements supports a finding of nexus,” J.A. 31–32
(emphasis in original). These findings are supported by
substantial evidence. Metrom’s secondary considerations
evidence “does not weigh in favor of nonobviousness.”
J.A. 33.
B
Metrom next contends that substantial evidence did
not support the Board’s determinations that claim 1 of each
patent was obvious over Grisham alone. The petitions as-
serted that Grisham alone rendered obvious each limita-
tion of claim 1 of each patent based on a single-reference
obviousness theory. Aside from its secondary-considera-
tions evidence, Metrom did not challenge petitioners’ con-
tentions regarding the obviousness of these claims over
Grisham in its patent owner responses. Although Metrom
made additional arguments in its sur-replies that these
claims were not obvious over Grisham, we see no error in
the Board’s conclusions that these arguments were
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 7
untimely and forfeited. J.A. 22 n.13; Rembrandt Diagnos-
tics, LP v. Alere, Inc., 76 F.4th 1376, 1383 (Fed. Cir. 2023)
(“We have held that in some circumstances the Board acts
within its discretion when declining to consider . . . a new
theory of patentability raised by patent owner in sur-re-
ply.”). Like the Board, we decline to consider these un-
timely arguments. We see no error in the Board’s
conclusions that claim 1 of each challenged patent are ob-
vious over Grisham.
C
Metrom argues that the Board erred in determining
that claims 2 through 4 of both the ’131 patent and the
’227 patent were unpatentable as obvious over the prior
art. Claim 2 of the ’131 patent, which is substantively
identical in relevant respect to claim 2 of the ’227 patent,
recites:
The collision avoidance system of claim 1, further
comprising:
a central tracking unit in communication
with the first vehicle mounted module and
the second vehicle mounted module,
wherein the central tracking unit is opera-
ble to track a location of the first vehicle
mounted module and a location of the sec-
ond vehicle mounted module.
’131 patent, claim 2 (emphasis added).3 Claims 3 and 4 of
both challenged patents depend from each patent’s
3 Claim 2 of the ’227 patent recites a central tracking
unit operable to “track the location” instead of tracking “a
location.” ’227 patent, claim 2 (emphasis added). Metrom
does not argue that the use of “a” in place of “the” meaning-
fully changes the scope of the claims.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 8
respective claim 2. Metrom makes no separate arguments
with respect to dependent claims 3 and 4.
The Board concluded that claim 2 of each patent and
their respective dependent claims were obvious over a com-
bination of Grisham and a second prior art reference, Doug-
las, U.S Patent No. 8,874,359 (“Douglas”) (filed
February 19, 2010) (issued Oct. 28, 2014). The Board
found that Douglas discloses “track[ing] the locations of
trains along specific tracks . . . relative to links . . . that
connect specific tracks to allow a specific train to switch
tracks at a particular location and within the limited zone
of station” and that this disclosure in Douglas “tracks loca-
tion as recited in claim 2.” J.A. 39 (citing J.A. 1608, col. 3
ll. 1–23).
Metrom contends that these claims require some level
of precise location tracking beyond that disclosed by Doug-
las. However, as the Board correctly noted, “the challenged
claims do not require any particular precision for train ‘lo-
cation.’” J.A. 38. Douglas’s disclosure thus is sufficient to
satisfy the “track a location” limitation, and we see no error
in the Board’s determination that the combination of Gri-
sham and Douglas renders claims 2 through 4 of both chal-
lenged patents unpatentable as obvious.
D
Finally, with respect to the Board’s unpatentability de-
terminations related to claim 7 of each patent, Metrom ar-
gues that the Board erred in determining that an
ordinarily skilled artisan would be motivated to combine
Grisham with Nixon to render these claims unpatentable
as obvious. Nixon discloses a collision-avoidance system
using GPS that “can be applied to any kind of vehicle, such
as an airplane, a boat, a ship, a train, a snowmobile and an
ATV.” J.A. 1749–50 (emphasis added). Petitioners pro-
posed combining Nixon’s GPS units with the UWB-based
system in Grisham and argued that “an ordinarily skilled
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 9
artisan would have been motivated to supplement Gri-
sham’s UWB-based collision avoidance system with
Nixon’s GPS units because UWB accuracy is range-limited
due to low transmission power that reduces its usefulness
in stopping long trains.” J.A. 55–56.
Metrom contends that the Board “ignored Metrom’s
proffered evidence that a[n ordinarily skilled artisan]
would have been concerned about interference from UWB
radios” and “relied on the conclusory opinions of [Peti-
tioner’s expert Scott] Andrews” to determine that there
was a motivation to combine Grisham and Nixon. Appel-
lant’s Br. 48.
The Board considered each of these arguments and
found, in light of competing evidence from petitioners, that
an ordinarily skilled artisan would be motivated to com-
bine Grisham and Nixon. This evidence included testi-
mony from Mr. Andrews that “an ordinarily skill[ed]
artisan would have augmented Grisham’s UWB-based sys-
tem with Nixon’s GPS because UWB has low transmission
power and would benefit from using GPS to measure the
absolute position and heading of vehicles,” J.A. 57 (citing
J.A. 1029–31), and Nixon’s express use of “GPS and UWB
in a collision avoidance system, which Nixon states can be
applied to a train.” J.A. 58 (emphasis in original) (citing
J.A. 1745–46, 1748–57). The Board’s motivation-to-com-
bine findings are supported by substantial evidence. The
Board properly determined that claim 7 of each challenged
patent was unpatentable as obvious over the combination
of Grisham and Nixon.
Accordingly, we affirm as to all issues raised in
Metrom’s appeal.
II
The sole issue presented by petitioners’ cross-appeal is
whether the Board erred in its determination that
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 10
claims 17–20 of the ’131 patent are not unpatentable as ob-
vious in light of Grisham’s express disclosures.4
Claim 17 recites:
[17Pre] A rail vehicle module mountable on a first
rail vehicle, the module comprising:
[17A] a transponder sensor module com-
prising:
[17B] a radio communication unit
operable to employ time of flight
techniques to detect a separation
distance between the first rail vehi-
cle and a second vehicle;
[17C] a first wireless communica-
tions antenna operable to send and
receive data representing the sepa-
ration distance over the air;
[17D] a global positioning system
unit operable to receive infor-
mation from one or more satellites
to determine an absolute position
of the first rail vehicle;
[17E] a control electronics module
comprising a processor in commu-
nication with the transponder sen-
sor module; and
[17F] a user interface module in-
cluding a user interface operable to
4 Petitioners argued that claim 17, from which
claims 18 through 20 depend, was unpatentable over a
combination of Grisham and Nixon. However, petitioners
only cite Grisham’s disclosures with respect to the chal-
lenged limitation.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 11
provide rail vehicle information to
a vehicle operator and to receive in-
put from the vehicle operator,
[17G] wherein the rail vehicle mod-
ule communicates with a second
rail vehicle module mountable on
the second vehicle to detect a sepa-
ration distance between the first
rail vehicle and the second vehicle.
’131 patent, claim 17 (emphases added).
The Board rejected petitioners’ obviousness arguments
with respect to claims 17–20 because the Board concluded
that limitation 17C was not disclosed in Grisham.
Understanding the Board’s determination that Gri-
sham does not disclose limitation 17C requires review of
the overall structure of claim 17 and its relationship to the
other claims. Earlier in the petition, with respect to
claim 1, Petitioners discussed how impulse radio signals
consisting of sequences of pulses are transmitted between
locomotives that are used to measure a total “time-of-
flight” difference between locomotives. As the Board artic-
ulated with respect to claim 1 in its final written decision,
describing Mr. Andrews’s testimony, the time-of-flight
technique refers to “using two sequences of pulses between
two transceivers, measuring a time difference between the
delayed first reference signal and the first [reference] sig-
nal, as the total time of flight of the sequences and the dis-
tance between the transceivers is determined from the time
difference.” J.A. 22 n.12 (internal quotations omitted) (cit-
ing J.A. 1000–01 ¶¶ 125–26). Similarly, the specification
of the ’131 patent describes transmitted radio signals as
“data [that] travel[s] from one UWB unit to the other” and
contemplates that “distance information may be computed
by determin[ing] how long it took” for this data to travel
between the locomotives. ’131 patent, col. 14 ll. 12–31.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 12
Claim 17 explicitly requires the use of the time-of-
flight technique to determine separation distance. Limita-
tion 17B requires “employ[ing] time of flight techniques to
detect a separation distance between the first rail vehicle
and a second vehicle.” Metrom did not argue that Grisham
failed to disclose limitation 17B. Limitation 17G specifies
that “the rail vehicle module communicates with a second
rail vehicle module mountable on the second vehicle to de-
tect a separation distance between the first rail vehicle and
the second vehicle.” Metrom also did not argue that Gri-
sham failed to disclose limitation 17G.
With respect to claim limitation 17C, “a first wireless
communications antenna operable to send and receive data
representing the separation distance over the air,” petition-
ers argued in the petition that Grisham’s radio units in-
clude antennas that “continuously transmit and receive
impulse radio signals wirelessly.” J.A. 4966. The petition
cites to Grisham’s specification, which describes how these
signals have “a known pseudorandom sequence of pulses.”
J.A. 1387 col. 23 ll. 42–47. Petitioners argued that the im-
pulse radio signals sent and received by Grisham’s anten-
nas “provide data such as direction, speed, and distance of
each rail vehicle (showing the separation distance between
trains).” J.A. 4966. Thus, petitioners clearly argued that
the “data representing the separation distance” was the
time-of-flight data, and that the transmission and receipt
of such data over the air was disclosed by Grisham.
In its patent owner response, Metrom’s argument as to
why claim 17 was not unpatentable as obvious consisted of
only three sentences, arguing that limitation 17C was not
obvious. In a figure of Grisham, “the only details displayed
are direction, speed and distance. There is no suggestion
that data representing the separation distance is commu-
nicated over the air.” J.A. 5252. Therefore, as Metrom ar-
gued, “[t]he combination of Grisham and Nixon does not
disclose ‘a first wireless communications antenna operable
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 13
to send and receive data representing the separation
distance over the air,’” as required by limitation 17C. Id.
(emphasis in original).
In reply, petitioners argued that “[t]he only way dis-
tance information is displayed [in Grisham] is if data rep-
resenting the separation distance is communicated over
the air.” J.A. 5412–13. Petitioners pointed out that “[t]he
exact details about how this separation distance is deter-
mined from the impulse radio signal (via the time of flight
technique) was described with respect to [17G] (where
Mr. Andrews refers back to [1J]).” J.A. 5413–14 (citing
J.A. 1039 ¶ 197; J.A. 1000–02 ¶¶ 125–27. Thus, both in
the petition and reply, petitioners argued that the data
used in the time-of-flight calculation is the claimed “data
representing the separation distance,” which is later used
to calculate a separation distance by the vehicle module.
In its sur-reply, Metrom argued that because Gri-
sham’s locomotives could independently calculate the sep-
aration distance using the time-of-flight technique, “there
is no need to transmit the separation distance,” i.e., the
computed distance. J.A. 5463. Metrom’s theory for the
first time suggested that “data representing the separation
distance” should be construed to mean the computed sepa-
ration distance, rather than the data that is used to com-
pute a separation distance using the time-of-flight
technique.
At the hearing, petitioners responded to Metrom’s the-
ory that “the second train makes that determination [com-
puting the separation distance] but it never sends that
information back to the first train” by arguing that Gri-
sham also disclosed transmitting the computed separation
distance between locomotives. J.A. 5639. Petitioners
quoted a sentence of Grisham’s specification, which was
cited in petitioners’ reply, that disclosed that the first loco-
motive “‘can contain the same equipment as the second
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 14
locomotive’” and “‘could be notified of the presence and
speed of an oncoming second locomotive,’” J.A. 5638–39
(quoting J.A. 1387 col. 24 ll. 25–29), and that separation
distance is “what’s meant by presence and speed here.”
J.A. 5640.
The Board concluded that petitioners failed to estab-
lish that claim limitation 17C was disclosed by Grisham.
J.A. 63–64. It agreed with Metrom that limitation 17C re-
quired transmitting the computed separation distance ra-
ther than the time-of-flight data that is used to compute
the separation distance, and that it was not obvious to
transmit the computed separation distance in Grisham.
This was so, the Board reasoned, because the locomotives
in Grisham could compute a separation distance from the
data used in the time-of-flight calculation, and thus it was
“not persuaded that Grisham requires ‘separation distance’
data to be communicated in order to determine or display
distance information.” J.A. 63–64 (emphasis in original).
It also found that Mr. Andrews’s testimony regarding the
data transmitted between the antennas in Grisham merely
“detail[ed] how distance may be calculated at the receiving
unit,” rather than describing how Grisham disclosed trans-
mitting an already-computed separation distance between
locomotives. J.A. 64. As such, it agreed with Metrom’s con-
tention that “‘there is no need to transmit the separation
distance” in Grisham. J.A. 64 (quoting J.A. 5463).
In reaching this conclusion, the Board’s critical error
was agreeing with the theory, advanced in Metrom’s sur-
reply, that the claim term “data representing the separa-
tion distance” means only the computed separation dis-
tance rather than data that is then used in the time-of-
flight calculation to compute a separation distance. This
construction is incorrect. Claim limitation 17C references
“the separation distance” calculated in limitation 17G, and
limitation 17B describes how separation distance is calcu-
lated using the time-of-flight technique. Claim 17B
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 15
explicitly requires “employ[ing] time of flight techniques to
detect a separation distance between the first rail vehicle
and a second vehicle,” and limitation 17G specifies that
“the rail vehicle module communicates with a second rail
vehicle module mountable on the second vehicle to detect a
separation distance between the first rail vehicle and the
second vehicle.” ’131 patent, claim 17 (emphases added).
This on its face requires that “data representing the sepa-
ration distance” is the data being used in the time-of-flight
technique “to detect a separation distance.”
Significantly, in Metrom’s complaint against petition-
ers in the related district court proceedings, Metrom itself
contended that “data representing the separation distance”
is “data used to determine the time of flight.” J.A. 1561.
Requiring “data representing the separation distance” to
be the computed separation distance, rather than the data
used to detect the separation distance, is incompatible with
the language and structure of the claim as a whole and
Metrom’s argument in the parallel district court proceed-
ing. The Board erred in construing “data representing the
separation distance” to be the computed separation dis-
tance rather than the data representing the separation dis-
tance that is used in the time-of-flight calculation.
As Metrom conceded at oral argument, Grisham dis-
closes transmitting data used in the time-of-flight tech-
nique over the air. Oral Arg. at 37:45–38:08. We conclude
that there is no dispute that Grisham discloses sending and
receiving data used to determine a separation distance us-
ing the time-of-flight technique over the air, which satisfies
claim limitation 17C.
In light of our determination, we need not reach peti-
tioners’ argument that Grisham expressly discloses trans-
mitting a computed separation distance between
locomotives. As Metrom does not challenge petitioners’
other obviousness contentions for claims 17–20 beyond
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 16
challenges that were already considered and rejected by
the Board with respect to other claims that the Board de-
termined to be unpatentable in both proceedings, we con-
clude that petitioners have shown that claims 17–20 of the
’131 patent are unpatentable as obvious. We reverse with
respect to petitioners’ cross-appeal.
The dissent argues that the petitioners did not argue
before the Board that “any pulses whose timing is used for
calculating separation distance (even when the signals en-
code nothing, much less separation distance) constitute
‘data representing the separation distance’ as a matter of
claim construction.” Dissent at 7 (emphasis in original).
But the issue was raised, even though it was not desig-
nated as a matter of claim construction. The petitioners
elaborated in their reply on the impulse radio signal theory
articulated in the petition, which clearly argued that the
“data representing the separation distance” is the data
used in the time-of-flight technique. The reply stated “[t]he
only way distance information is displayed [in Grisham] is
if data representing the separation distance is communi-
cated over the air. . . . The exact details about how this sep-
aration distance is determined from the impulse radio
signal (via the time of flight technique) was described with
respect to [17G] (where Mr. Andrews refers back to [1J]).”
J.A. 5413. The patentee had the opportunity to respond in
its sur-reply. The Board considered the reply and did not
suggest that the reply unfairly exceeded the theory in the
petition. J.A. 64. Faulting petitioners for not raising claim
construction seems unfair because it was Metrom in its
sur-reply and the Board in its final written decision that
adopted the implied and incorrect claim construction.
On appeal, the petitioners expressly argued that Gri-
sham discloses limitation 17C. To be sure, petitioners’ ap-
pellate briefing does not do a good job of explaining this
issue, but we may exercise our discretion to “overlook such
failures and address the merits.” 16AA Wright & Miller,
Federal Practice & Procedure § 3974.1 (5th ed. 2026). This
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 17
is particularly so where, as here, the issue was presented
to the Board in the first instance.
We have considered Metrom’s remaining arguments
and find them unpersuasive.
AFFIRMED-IN-PART AND REVERSED-IN-PART
COSTS
Costs to appellees/cross-appellants.
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N OTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
METROM RAIL, LLC,
Appellant
v.
SIEMENS MOBILITY, INC., HITACHI RAIL GTS
USA INC., FKA GROUND TRANSPORTATION
SYSTEMS USA INC., HUMATICS CORP., PIPER
NETWORKS, INC.,
Cross-Appellants
______________________
2024-2223, 2024-2236, 2024-2264
______________________
Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2023-
00468, IPR2023-00470.
______________________
T ARANTO, Circuit Judge, concurring-in-part and dissent-
ing-in-part.
I join the court’s opinion except with respect to claims
17–20 of the ’131 patent, as to which I respectfully dissent.
The court’s decision reversing the Board’s upholding of
those claims rests on the court’s own claim construction of
Claim 17’s disputed element (17C), a construction the court
adopts based on its relationship to elements 17B and 17G.
See Op. 14 (“critical error” is one of “construction”). But
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 2
Siemens did not present or develop this construction in
challenging the Board’s ruling on claims 17–20 in this
court; indeed, it did not present a claim-construction argu-
ment at all, but only an argument that the Board misread
the prior-art reference, Grisham. Siemens Cross-Appeal
Br. at 3 (statement of issue), 64–70 (argument). Nor did
Siemens urge the court’s claim construction before the
Board. We should not be sua sponte deciding the cross-ap-
peal on this basis, given the important principles of party
presentation and adequate preservation. See Clark v.
Sweeney, 607 U.S. 7, 9 (2025) (the court “transgressed the
party-presentation principle by granting relief on a claim
that [the appellant] never asserted and that [the appellee]
never had the chance to address”); In re Google Technology
Holdings LLC, 980 F.3d 858, 863 (Fed. Cir. 2020) (party
forfeited claim-construction arguments by failing to pre-
sent them to the Board).
A
The Board found that Grisham does not teach Claim 17
for a simple reason. See Siemens Mobility, Inc. v. Metrom
Rail, LLC, IPR2023-00468, 2024 WL 3048533, *27
(P.T.A.B June 18, 2024) (Decision). Grisham undisputedly
discloses certain elements of claim 17, including the ele-
ments (17B and 17G) highlighted in the court’s analysis.
Thus, in Grisham, a “first rail vehicle” sends over-the-air
“impulse radio signals” to a “second vehicle,” which allows
a “radio communication unit” within a “rail vehicle module
mountable on” the first vehicle to calculate, from the time
of “flight” (the amount of time it takes a signal to travel
between the trains), a distance between the two trains (“to
employ time of flight techniques to detect a separation dis-
tance between” the vehicles, as required by 17B). It is also
undisputed that Grisham discloses a “rail vehicle module
mountable on” the first vehicle that “communicates with” a
“rail vehicle module mountable on” the second vehicle “to
detect a separation distance between” the two trains (as re-
quired by 17G). Decision, at *2–3; see J.A. 4965–66
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 3
(petition); J.A. 5251–52 (patent owner response). And it is
undisputed that the time of flight is calculated simply by
using “time position measurement to measure a propaga-
tion delay,” i.e., noting and comparing the timing of signals
(such as pulse signals) and calculating distance based on
that timing, not by using any encoding of information in
the signals. Decision, at *9 & n.12; see Pet. 18–19; J.A. 957,
1001–02 (Siemens expert declaration, ¶¶ 50, 126–27). In
short, “[t]he separation distance may be measured by de-
termining how long it takes a pulse to travel between two
transceivers, which is [ ] referred to as ‘Time of Flight’
(TOF).” Pet. 6.
What is missing in Grisham, the Board ruled, is what
element 17C requires—that the first vehicle’s “communica-
tions antenna” is “operable to send and receive data repre-
senting the separation distance over the air” (17C
(emphasis added)). The Board found that the only part of
Grisham that Siemens’s petition relied on for the 17C-re-
quired over-the-air communications did not show over-the-
air communication of data representing the separation dis-
tance. Decision, at *26–27. In particular, the Board re-
jected Siemens’s submission, in its petition (and
accompanying expert declaration), that Grisham’s Figure
22 showed over-the-air communication of data represent-
ing the separation distance. Id.; see J.A. 4966 (petition);
J.A. 1037 ¶ 192 (expert).
Grisham’s Figure 22 was the heart of Siemens’s case as
relevant here:
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 4
J.A. 1375. Importantly, in Figure 22, the first four steps
(2202, 2204, 2206, and 2208) are over-the-air transmitting
and receiving of impulse radio signals (pulses), the timing
of which is used for time-of-flight calculations to determine
a distance. In contrast, the last step (2212) is about dis-
playing certain distance (and other) information, stating:
“show details about first locomotive (e.g., Direction, Speed,
Distance).”1
1 The first four steps are versions of the first four
(pulse) steps of Grisham’s flowchart, Figure 10, which de-
tails the steps for Grisham’s Figure 9—relied on by the
Board for various claim elements other than 17C. See J.A.
1363, 1384–85 (Grisham, Figs. 9, 10 and col. 18, line 58,
through col. 19, line 19); Decision, at *27.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 5
Element 17G is similar to claim 1’s element 1J, and
Siemens pointed, for its assertion that Grisham taught
17G, to its analysis of why Grisham taught 1J. See J.A.
4966 (petition); J.A. 1039 (expert, ¶ 197). Element 1J
reads, “the first vehicle mounted module and the second
vehicle mounted module are operable to apply a time of
flight technique to determine a separation distance be-
tween the first rail vehicle and the second rail vehicle.”
(emphasis added). For that element, Siemens relied on the
calculation made from the timing of the impulse radio sig-
nals (shown in the first four steps of Figure 22 and parallel
Figure 10), not on any suggestion that separation distance
was represented by the data encoded in those signals. See
Pet. 17–19; J.A. 1000–02 (expert, ¶¶ 125–27).
In contrast, when Siemens and its expert asserted that
Figure 22 teaches element 17C, they never stated that the
first four steps (transmission and receipt of impulse radio
signals) themselves constituted the over-the-air transmis-
sion and receipt of data representing the separation dis-
tance simply because the signals’ timing is used to
calculate a distance (by a time-of-flight method that does
not rely on any encoding of information in the signals at
all). That simple point is what Siemens would have made
had it been advancing the claim construction adopted by
the court today. It did not do so. Instead, for its contention
that Grisham disclosed 17C, Siemens relied, at the petition
stage and also at the reply stage, on certain arguments
keyed to the reference in the last step to “distance” (2212,
referring to display of “direction, speed, and distance”).
That reliance was wholly unnecessary if bare use of the
timing of pulse signals for a distance calculation is enough
as a matter of claim construction.
In particular, Siemens made the following two submis-
sions invoking step 2212. First, it made an unelaborated
assertion that, in Figure 22, “[t]he signals provide data
such as direction, speed, and distance of each rail vehicle
(showing the separation of distance between trains).” J.A.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 6
4966 (petition, citing Figure 22); see also J.A. 1037 (expert
¶ 192) (“The signals can include data such as direction,
speed, and distance of each rail vehicle.”) (citing Figure 22)
(emphasis added). In other words, Siemens declared that
the pulse signals can encode the three kinds of information
listed in step 2212. Siemens made its second assertion af-
ter Metrom responded to the first assertion by arguing that
actually “[t]here is no suggestion [in Figure 22] that data
representing the separation distance is communicated over
the air,” J.A. 5252, i.e., that the signals in Figure 22’s first
four steps actually are encoded with such information. Sie-
mens’s new point was that such communication must be
occurring in Grisham: “The only way distance information
is displayed is if data representing the separation distance
is communicated over the air.” J.A. 5413. It added that
the “exact details about how this separation distance is de-
termined from the impulse radio signal (via the time of
flight technique) was described with respect to [17G] where
[Siemens’s expert] refers back to [1J]).” Id. (emphasis
added). The second sentence is only about how separation
distance “is determined from the impulse radio signal”; it
does not even purport to support the idea that the impulse
signals are encoded with the separation distance infor-
mation, let alone assert, as a matter of construction, that
the signals always qualify as data representing the separa-
tion distance. Contra Op. 15–16.
The Board rejected Siemens’s argument. The Board
found that nothing in Grisham timely identified by Sie-
mens for its 17C mapping indicates that the impulse radio
signals encode data representing the train-separation dis-
tance; after all, the time-of-flight calculation disclosed in
Grisham relies only on the timing of the signals, not infor-
mation they may encode. And the Board found that Gri-
sham does not suggest that over-the-air communication of
that distance is necessary; after all, a train that can calcu-
late the distance (from impulse timing) need not have that
result sent to it. Decision, at *26–27.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 7
B
The court’s opinion does not rest on a showing that the
Board was wrong in its analysis of Grisham and Siemens’s
submissions about it. Rather, the court concludes that the
Board’s conclusion was incorrect as a matter of claim con-
struction. The court’s adopted construction is that any sig-
nals (even those not encoding anything, much less
separation distance) sent over the air, as long as the timing
of the signals is used to make a time-of-flight-based calcu-
lation of the separation distance between the trains, them-
selves constitute “data representing the separation
distance” sent and received “over the air” under element
17C. Op. 14–15. The court draws this construction from
its understanding of elements 17B and 17G. Id.
Siemens, however, did not make such a claim-construc-
tion argument, or any claim-construction argument at all,
in its cross-appeal brief to us. Siemens argued only that
the Board misunderstood Grisham, which presents a fac-
tual issue; and it relied for that argument overwhelmingly
on a five-line passage in Grisham (J.A. 1387, col. 24, lines
25–29) on which it did not rely in its petition’s detailing of
why Grisham taught element 17C (J.A. 4966). Siemens
Cross-Appeal Br. at 3, 64–70. It would have been a simple
matter for Siemens to assert—though a much less simple
matter to try to defend the assertion—that signals sent to
be used for time-of-flight calculations qualify on that basis
alone as data representing the separation distance. Sie-
mens did not do so.
Siemens’s choice in this court reflects its presentation
to the Board. As summarized above, Siemens did not say
that any pulses whose timing is used for calculating sepa-
ration distance (even when the signals encode nothing,
much less separation distance) constitute “data represent-
ing the separation distance” as a matter of claim construc-
tion. Had that been Siemens’s position, the task for
Siemens and its expert regarding element 17C, relying on
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 8
Grisham’s Figure 22, would have been trivial: They would
have simply pointed to steps 2202, 2204, 2206, and 2208,
which, regardless of step 2212 and regardless of any data
content of the signals, would have been enough. They
never did so at any stage of the Board proceedings. Sie-
mens never proposed the construction adopted by the court
today—or, therefore, provided a supporting claim-con-
struction analysis, much less one based (like the court’s) on
inferences from elements 17B and 17G.
Compelling confirmation of the absence of such a posi-
tion is apparent from the oral argument before the Board
(after the reply and sur-reply). A Board judge asked Sie-
mens specifically about Metrom’s contention that, after the
train calculates the separation distance, “it never sends
that information” to the other train (as Siemens summa-
rized the contention). J.A. 5639. If Siemens had been ad-
vancing the court’s claim construction, its answer would
have been simple: It would have said that no over-the-air
sending of the distance result was needed because the send-
ing of the pulses used to make the distance calculation al-
ready met the 17C requirement. It did not. Instead,
Siemens’s response, referring to the Board judge’s question
about sending the distance result over the air, was, “But
Grisham does do that,” J.A. 5639, followed by a reference
to the five-line passage from Grisham that it had not relied
on for 17C in the petition, id. Counsel then elaborated that
the calculating train really should inform the other train of
the separation distance, J.A. 5639–40, and sought to trans-
late the language used in the Grisham passage (“presence
and speed”) into the different language of 17C (“the sepa-
ration distance”), J.A. 5640. Again, that argument—pre-
senting evident difficulties of substance and
preservation—would have been wholly unnecessary had
Siemens been advancing the claim construction on which
the court today relies.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 9
In these circumstances, there is a double forfeiture—in
this court and before the Board—of the claim construction
adopted by the court.
If there exist some claim-construction issues that are
so easy to resolve that we could properly decide them de-
spite such double forfeiture, this is not one of them. Even
aside from the absence of exceptional circumstances excus-
ing the forfeitures, we lack a complete claim-construction
analysis. We have no analysis, from intrinsic or extrinsic
evidence, of what “data representing the separation dis-
tance” means—and whether that phrase should cover a
simple pulse (not encoding any meaning) whose departure
and return timing can be used to calculate the distance.
Moreover, the only basis the court recites for its conclusion
about 17C is an inference based on 17B and 17G, but the
inference has not been justified, let alone shown to be
clearly compelled (so as to make full claim-construction ar-
guments pointless). Neither says anything about the “data
representing” phrase of 17C. 17B says that a unit “em-
ploy[s] time of flight techniques to detect a separation dis-
tance,” which does not imply that signals used as inputs
into the time-of-flight calculation are data representing the
calculation’s result or that the result is sent over the air.
The same is true of 17G, which simply adds that the second
vehicle, like the first, has a “rail vehicle module” mounted
on it and the first vehicle’s module communicates with that
module to detect a separation distance between them. Fi-
nally, the court cites in passing Metrom’s complaint in a
related district court proceeding, which states that “data
used to determine the time of flight” constitutes “data rep-
resenting the separation distance,” J.A. 1561 (cited at Op.
15), but the parties in the present proceeding have not re-
lied on that statement at all, much less explored its signif-
icance for a claim construction position never advanced
here.
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METROM RAIL, LLC v. SIEMENS MOBILITY , INC. 10
C
Because I conclude that we should not decide the cross-
appeal on the basis set forth in the court’s opinion, I ad-
dress the argument Siemens has actually made to us re-
garding claims 17–20. That argument relies
overwhelmingly on the five-line Grisham passage noted
above, J.A. 1387 (Ex. 1006), col. 24, lines 25–29. We should
readily reject that reliance.
We have recognized that the Board’s determination
that a particular theory was not adequately presented in a
petition is subject to review only for abuse of discretion.
See Netflix, Inc. v. DivX, LLC, 84 F.4th 1371, 1376 (Fed.
Cir. 2023). Here, there was no such abuse. It is plain that
Siemens did not rely on that passage in its petition’s
presentation of how Grisham disclosed element 17C. See
J.A. 4965–66 (showing no reference to J.A. 1387, col. 24,
lines 25–29). And as indicated by Siemens’s new featuring
of this passage, the Board could reasonably deem the pas-
sage to be materially different from—not just a small elab-
oration of—what Siemens did cite for its petition’s 17C
argument and, also, raising new interpretive issues of its
own. In these circumstances, the Board did not commit re-
versible error in not allowing Siemens to rely on this pas-
sage late in the process. With no such error in that respect,
there is no basis for disturbing the Board’s decision to up-
hold claims 17–20.
For the foregoing reasons, I would affirm the Board
with respect to claims 17–20.
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