IP Law Daily, PATENT—Fed. Cir.: PTAB’s decision invalidating a patent on monitoring trains affirmed, (Jul 28, 2026)

By Carolin Dennis, B.Sc., LL.B., LL.M.

A patent owner’s bid to revive a patent on monitoring trains was denied as substantial evidence supported the Patent Trial and Appeal Board’s findings.

In a non-precedential disposition, the U.S. Court of Appeals for the Federal Circuit affirmed the decision of the Patent Trial and Appeal Board (PTAB) that claims of Amsted Rail Co. Inc.’s patent on monitoring trains were unpatentable as obvious over prior art. The Federal Circuit found no error in the PTAB’s claim construction, factual findings, or denial of the motion to amend (Amsted Rail Co., Inc. v. Squires, No. 25-1063 (Fed. Cir. Jul. 24, 2026)).

Amsted Rail Co., Inc. (Amsted) owns U.S. Patent No. 10,137,915 (’915 patent) that claims systems and methods of detecting and analyzing operational anomalies in trains. Amsted sued its former research and development director and a company he formed called Hum Industrial Technology, Inc. (Hum Industrial) in 2022 alleging trade secret theft and infringement of patents relating to measuring the acceleration of railcars to improve safety. Hum Industrial petitioned for inter partes review arguing claims 1, 21–30, 36, and 37 of the ’915 patent are unpatentable under 35 U.S.C. § 103. After institution, Amsted filed a contingent motion to amend to substitute claims 38–48 in the event any challenged claims were held unpatentable. The PTAB ultimately held all challenged claims unpatentable and denied Amsted’s motion to amend. In so doing, the PTAB relied on four prior art references: U.S. Patent Application Publication No. 2011/0282540 (Armitage), U.S. Patent Application Publication No. 2007/0208841 (Barone), LeFebvre, and Winfree. Amsted appealed the final written decision of the PTAB determining all the challenged claims claims of the ’915 patent unpatentable under 35 U.S.C. § 103 and denying Amsted’s motion to amend.

Amsted argued that the PTAB erred in its construction of claim 1 of the ’915 patent, because, in its view, claim 1’s sensor must first “sense” or “measure” the accelerations before the filter “filter[s] at least a portion of the accelerations.” The PTAB rejected Amsted’s position that claim 1 filters “already measured accelerations.” The Federal Circuit agreed with the PTAB that claim 1 does not require any specific order for the performance of the sensor and filter functions. Moreover, as the PTAB observed, Amsted’s construction would clash with dependent claim 23, which recites that “the one or more filters” of claim 1 “are disposed to remove the undesirable accelerations before the undesirable accelerations reach the one or more sensors that are configured to measure accelerations.” Dependent claim 23 therefore lends strong support to the PTAB’s construction that claim 1’s filter function need not occur after the sensor function. The Federal Circuit was also unpersuaded by Amsted’s assertion that claim 23 was drafted in error, a proposition for which Amsted cited no record support. Accordingly, the PTAB did not err in construing claim 1.

Next, the Federal Circuit also disagreed with Amsted’s argument that the PTAB lacked substantial evidence to find a motivation to combine Armitage and Barone. When analyzing the motivation, the PTAB relied on Barone’s “removal of unwanted data.” The PTAB explained that Barone’s data filtering technique could be predictably applied to Armitage’s system with the benefit of improving data processing. The Federal Circuit found that substantial evidence supported the PTAB’s finding, as the PTAB reasonably credited Hum Industrial’s expert Mr. Ricca, who opined that a skilled artisan would have been motivated to employ Barone’s principle of removing “unwanted data” in Armitage’s system. Further, Amsted also argued that the PTAB lacked substantial evidence in finding that the Armitage-Barone combination disclosed limitation 25[d], which requires a “software filter” executed on “firmware.” Amsted specified that the PTAB failed to explain why Barone’s analog filtering could operate on Armitage’s digital firmware. The PTAB agreed with Amsted that Barone disclosed “analog, not digital” filtering, but further explained that Amsted misunderstood Hum Industrial’s argument, which was that a skilled artisan would have implemented Barone’s general filtering principle in Armitage’s existing firmware because Barone’s filtering principles “electronically, mechanically, and digitally.” Therefore, notwithstanding Barone’s analog filtering, substantial evidence supported the PTAB’s conclusion that a skilled artisan would understand Barone’s general principle of removing unwanted data would be performed by a software filter executed on Armitage’s firmware.

Lastly, the Federal Circuit addressed Amsted’s argument that the PTAB incorrectly denied its motion to amend with substitute claims after concluding they would be unpatentable under § 103. Substitute claim 38 introduces three new limitations: a tri-axis sensor configured to measure accelerations along a plurality of axes, a “plurality of filters,” and a “plurality of detectors.” Amsted contended that Armitage was only configured to measure accelerations in one axis and therefore failed to teach measuring, filtering, and detecting accelerations in all three axes.

However, the Federal Circuit noted that the PTAB relied on Armitage paragraph 45 and Mr. Ricca’s opinion to conclude that a skilled artisan would understand Armitage’s 3-D accelerometer to measure accelerations in all three axes. Thus, the PTAB reasonably found this means that Armitage monitors more than one axis in other instances, and its accelerometer is not exclusively configured to monitor only one axis. Mr. Ricca also opined that the pluralities of filters and detectors require simple duplications of hardware that would be obvious to a skilled artisan. Accordingly, the Federal Circuit found no error in the denial of the motion to amend.

Accordingly, the PTAB’s determination was affirmed.

The Case is No. 25-1063.

Judge: Chen, R.

Attorneys: Ryan North Miller (Fox Rothschild LLP) for Amsted Rail Co., Inc. Shehla Wynne, U.S. Patent and Trademark Office, for John A. Squires.

Companies: Amsted Rail Co., Inc.

Cases: Patent FedCirNews