IP Law Daily, PATENT—Fed. Cir.: Invalidity of MIT’s dual-fuel engine technology patents affirmed on appeal, (Jan 2, 2026)

By Saurabh Kashyap, B.A., M.A., LL.B., LL.M.

PTAB correctly found the claimed fuel systems to be obvious in light of the cited prior art and applied the correct claim construction standard.

In a precedential disposition, the U.S. Court of Appeals for the Federal Circuit upheld final written decisions of the Patent Trial and Appeal Board (PTAB) in three inter partes review (IPR) proceedings initiated by Ford Motor Company, affirming the unpatentability of multiple claims in patents covering dual-fuel management systems for spark-ignition engines. The patents, owned by the Massachusetts Institute of Technology (MIT) and exclusively licensed to Ethanol Boosting Systems, LLC (EBS), were found to be obvious under 35 U.S.C. § 103. The court rejected EBS’s arguments that the PTAB exceeded its statutory authority, misapplied claim construction principles, and improperly assessed the prior art (Ethanol Boosting Sys., LLC v. Ford Motor Co., Nos. 24 -1381, 24 -1382, 24 -1383 (Fed. Cir. Dec. 23, 2025)).

Background. EBS and MIT are collaborators in developing combustion technologies designed to enhance fuel efficiency in internal combustion engines by mitigating engine knock. MIT owns the patents-in-suit, exclusively licensed to EBS. Ford Motor Company is a global automotive manufacturer. The Director of the U.S. Patent and Trademark Office intervened in the proceedings but did not independently brief the substantive issues.

The patents at issue, U.S. Patent Nos. 10,619,580 (the ’580 patent), 10,791,760 (the ’760 patent), and 9,708,965 (the ’965 patent) relate to a fuel management system combining direct injection (DI) and port fuel injection (PFI) to optimize combustion under different engine loads. The ’580 and ’760 patents focus on torque-based injection control, while the ’965 patent uses manifold pressure as the control variable. A common element across all patents is a “three-way catalyst” for reducing emissions. The claimed systems dynamically shift the fuel source from PFI to DI under high torque or pressure to avoid knock by introducing anti-knock agents directly into the combustion chamber.

In 2020, EBS sued Ford in district court, asserting infringement of all three patents. A key dispute was the meaning of the DI Fuel terms such as “directly injected fuel” and “fueling system that uses direct injection.” The district court adopted Ford’s proposed construction requiring that (1) the DI fuel differ from PFI fuel, and (2) the DI fuel include an anti-knock agent other than gasoline. Based on that construction, the court granted summary judgment of noninfringement. EBS appealed only the first part of the construction.

While litigation proceeded, Ford filed IPR petitions in December 2020, initially denied by the PTAB based on the district court’s narrow construction. However, after the Federal Circuit’s ruling in Ethanol Boosting Sys., LLC v. Ford Motor Co., No. 21-1949, 2022 WL 2798395 (Fed. Cir. July 18, 2022) (EBS I), which reversed the district court’s “different fuel” construction, the PTAB granted rehearing in November 2022 and instituted all three IPRs. In final written decisions issued in November 2023, the PTAB found all challenged claims unpatentable as obvious. EBS appealed.

Institution challenge. EBS argued that the PTAB’s decision to delay ruling on Ford’s rehearing request for over a year, pending the Federal Circuit’s decision in EBS I, was ultra vires and rendered the institution improper. The Federal Circuit rejected the argument, holding that 35 U.S.C. § 314(d) bars judicial review of institution decisions, including decisions on rehearing. Citing Thryv, Inc. v. Click-To-Call Techs., LP, 590 U.S. 45 (2020), and Medtronic, Inc. v. Robert Bosch Healthcare Sys., Inc., 839 F.3d 1382 (Fed. Cir. 2016), the court emphasized that even characterizing the PTAB’s delay as a “stay” did not change the essential nature of the challenge—it was an attack on the decision to institute review, and thus unreviewable.

Claim construction of “fuel.” EBS also argued that the PTAB was bound by the unappealed portion of the district court’s construction, which excluded gasoline as a qualifying anti-knock agent. The Federal Circuit disagreed, holding that doctrines such as the law of the case and mandate rule do not apply across distinct proceedings. It declined to impose judicial estoppel, noting that EBS failed to raise the issue meaningfully in its appeal briefs.

On the merits, the court affirmed the PTAB’s adoption of the plain and ordinary meaning of “fuel,” which included gasoline. The specification disclosed embodiments operating solely on gasoline, undermining EBS’s proposed exclusion. Citing Oatey Co. v. IPS Corp., 514 F.3d 1271, 1276 (Fed. Cir. 2008), the court reaffirmed the principle that claims should not be construed to exclude disclosed embodiments absent clear disavowal. The court found no such disavowal and noted EBS’s own admissions in prior litigation that gasoline was contemplated as an anti-knock agent.

Motivation to combine references. The PTAB found that a skilled artisan would have been motivated to combine U.S. Patent No. 6,505,603 (Schray), which teaches dual DI injection, with Japanese Patent JP2003013785 (Miura), which teaches PFI to suppress knock. The Federal Circuit held that the PTAB’s rationale was supported by substantial evidence. The Board accepted Ford’s argument that replacing Schray’s early DI injection with Miura’s PFI would improve combustion stability and reduce complexity. The court emphasized that the Board need not require a perfect match of homogeneity or injection timing for an obviousness finding, relying on KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398 (2007) and Intel Corp. v. PACT XPP Schweiz AG, 61 F.4th 1373, 1380 (Fed. Cir. 2023).

The second obviousness ground combined German Patent DE19853799 (Rubbert), which teaches fuel mixtures and variable injection, with Japanese Patent JPH10252512 (Yuushiro), which discloses fuel maps based on torque, and the Bosch Automotive Handbook. The court affirmed the PTAB’s conclusion that this combination rendered the claims obvious. It found that the PTAB properly credited expert testimony regarding how Yuushiro’s fuel map would enhance Rubbert’s system by optimizing knock control. Arguments based on prior institution decisions were rejected as distinguishable, given the more robust record developed during the instituted proceedings.

Anticipation vs. obviousness. Further, EBS contended that the PTAB impermissibly relied on a theory of anticipation for the “three-way catalyst” and “torque range” limitations, rather than an obviousness rationale. The court rejected this, finding that the Board properly incorporated these disclosures into its obviousness analysis and did not mischaracterize the nature of the grounds.

The Case is Nos. 24 -1381, 24 -1382, 24 -1383.

Judge: Chen, R.

Attorneys: Steven M. Seigel (Susman Godfrey LLP) for Ethanol Boosting Systems, LLC and Massachusetts Institute of Technology. Andrew James Ligotti (Alston & Bird LLP) for Ford Motor Co. Micheal S. Forman, Office of the Solicitor, USPTO, for John A. Squires.

Companies: Ethanol Boosting Systems, LLC; Massachusetts Institute of Technology; Ford Motor Co.

MainStory: TopStory Patent FedCirNews USPTO