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IP Alert: Federal Circuit Holds Mechanical Engineering Patent-Ineligible Under Section 101

October 9, 2019

The Federal Circuit and Supreme Court have frequently discussed the patent eligibility statute, 35 U.S.C. § 101, as it applies to patents in the fields of computer science and medical diagnostics. On October 3, in American Axle & Mfg., Inc. v. Neapco Holdings LLC, the Federal Circuit seemingly broadened the scope of ineligible subject matter to patents in the mechanical engineering arts, and in so doing, created further uncertainty about what a patentee needs to do to meet the requirements of section 101. The court specifically addressed whether certain claims directed to a method of manufacturing a shaft assembly of a driveline system constituted patentable subject matter when the claims represented an application of a natural law of mechanical engineering.

American Axle contended that Neapco infringed U.S. Patent No. 7,774,911. The asserted claims recited a method of manufacturing a shaft assembly having a hollow shaft member with a liner tuned to attenuate at least two types of vibrations encountered by the shaft during use in a vehicle (bending, shell, and torsion mode vibrations).

The use of liners to attenuate vibration in a driveline shaft was known in the art. However, prior art systems used liners to dampen only one of the three types of vibration experienced by shafts, not at least two types of vibrations as claimed. The district court held the claims to be ineligible for patent protection, and American Axle appealed.

On appeal, a majority of the assigned Federal Circuit panel applied the two-step test established by the Supreme Court for determining patentability under 35 U.S.C. § 101. Specifically, the first step determines whether the claims at issue are directed to a patent-ineligible concept, which includes laws of nature, natural phenomena, or abstract ideas. If so, the second step determines whether the claims contain additional elements that "transform the nature of the claim" into a patent-eligible application—an inventive concept.

With respect to step one, Neapco asserted that tuning the liner was merely the application of Hooke’s law. Hooke’s law is a natural law of physics that mathematically relates the mass and stiffness of an object to the frequency at which it vibrates. Neapco relied on testimony from the inventor and American Axle’s expert that tuning the liner included altering the mass or stiffness of the liner.

American Axle attempted to distinguish the claims from Hooke’s law by explaining that the liners were very complex systems with a density and stiffness that changed throughout, based on the local vibrations experienced by the proximate portion of the shaft. The court ruled for Neapco, dismissing American Axle’s argument because the distinction relied on was not recited in the claims. Accordingly, the court held that the claims were directed to a natural law rather than a specific method of implementing it.

Turning to step two of the eligibility analysis, the court held that nothing in the claims qualified as an “inventive concept” sufficient to constitute patentable subject matter. American Axle argued that liners had never been tuned to damp two different modes of vibration simultaneously. However, the court again found that this amounted to applying Hooke’s law through trial and error.

In a sharply worded dissent, Judge Moore criticized the majority for effectively ignoring the second part of the Alice/Mayo two-part test. Judge Moore asserted that the majority had basically repeated its response to part one by simply stating that the claimed method was merely applying Hooke’s law. Judge Moore further criticized the majority for finding not that the claims were directed to a specific natural law but to “Hooke’s law and possibly other natural laws.” In contrast, Judge Moore found that the claims recited numerous elements constituting inventive concepts. She also criticized the procedural posture, commenting that the appeal was from a summary judgment finding. On summary judgment, overturning the invalidity finding only required a question of fact over whether or not the claims recited an inventive concept.

The American Axle ruling appears to have added to the uncertainty about what constitutes patentable subject matter under 35 U.S.C. § 101. One aspect that stands out is the court’s focus on the absence of a specific method or mechanism of achieving the desired results in the claims: “Most significantly, the claims do not instruct how the variables would need to be changed to produce the multiple frequencies required to achieve a dual-damping result, or to tune a liner to dampen bending mode vibrations.” Patent applicants and litigants facing an invention that involves a law of mechanical engineering should consider whether there are claims that focus on specific structure for achieving the stated result.

Fitch Even will monitor the American Axle case for any subsequent developments. In the meantime, please contact Fitch Even partner Mark W. Hetzler with any questions concerning this decision.

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