Method For Manufacturing Drive Shafts Held Patent-Ineligible

  • October 1, 2019
American Axle & Mfg. v. Neapco Holdings, No. 18-1763

In American Axle, the Federal Circuit held that the patent claims directed to a method for manufacturing propeller drive shafts were not patent-eligible, as the claims were directed to a natural law and failed to describe a specific method for applying the natural law.

American Axle alleged Neapco infringed its patent for manufacturing propeller drive shafts having tuned liners to reduce shaft vibrations. Specifically, the patent alleged that drive shafts were susceptible to multiple modes of vibration, such as bending, torsion and shell vibration modes, each of which had to be dampened separately with prior art methods. The patent claimed methods for tuning drive shaft liners to dampen multiple types of vibration simultaneously.

Neapco moved for summary judgment, arguing that the claims were not patent-eligible because they were directed to a natural law, namely, Hooke’s law. Hooke’s law describes the relationship between the mass and/or stiffness of an object to the frequency of that object’s vibration. American Axle argued that tuning the liner amounted to more than an application of a natural law because the result of the tuning was unconventional. The district court agreed with Neapco that the claims amounted to instructions to apply Hooke’s law using conventional steps and granted Neapco’s motion. American Axle appealed to the Federal Circuit.

The Federal Circuit affirmed the finding of subject matter ineligibility. The court analyzed American Axle’s patent under the two-step Mayo/Alice framework. At step one, the court determined that the claims were directed to at least one natural law and that the claimed instruction to tune the liner merely amounted to an application of the natural law because the claims failed to describe a specific tuning process. At step two, the court determined that nothing in the claims qualified as an inventive concept because the claims described only conventional processes, even if the results would be new and unconventional. While American Axle argued that the process was more complex than a mere application of Hooke’s law, the Court countered that none of the mechanisms allegedly used to achieve the desired results were actually claimed in the patent.

Key Takeaway: Patents directed to a new or desirable method for applying a natural law must ensure that the claims actually recite the new process. A patent that merely claims applying a natural law and achieving a new result, may be invalid for failing to claim patent-eligible subject matter.


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