Mechanical Engineering Patents and Validity Goulash


If you thought that issues of natural law and abstract ideas were invalidating only medical device and treatment patents, think again.  The fog of natural law/natural phenomena/abstract ideas is descending upon “nuts and bolts” mechanical engineering.  It is no longer safe to pursue patent protection for vibration dampened drive shafts without encountering “validity goulash”.  


Again it may be useful to review my prior blog of Patenting Medical Devices and Procedures.  This will provides some background to the court decisions that fuel the controversy and confusion.

Further it is necessary to understand that laws of nature, natural phenomena, and abstract ideas are not patentable.  This is an application of 35 USC Section 101 and has been repeated by the Supreme Court in Mayo v. Prometheus, etc. 

Finally, it is useful to understand the patent in question merely claimed a method of building a vibration dampening drive shaft.  It did not claim the actual drive shaft which would have required described the actual physical structure of the drive shaft.

The latest dispute regarding patentability and the issue of “natural laws” arises in American Axle & Manufacturing v. Neapco Holdings decided Thursday, October 3, 2019.  The decision was made by a three justice panel of the Circuit Court of Federal Appeals.  The case pertains to a method of constructing an improved drive shaft that comprises a cylindrical shaft surrounded by a vibration dampening liner.  The method claims (i) tuning a liner to attenuate two types of vibration through the shaft member and (ii) the liner is configured to damp shell mode vibration 2 % and tuned to damp bending mode vibrations, to within about +/-20 % of a bending mode natural frequency.

There appear to be three things going on this case.  First the court identifies three types of vibration in a load bearing rotating shaft, i.e., bending mode vibration, torsion mode and shell mode vibration.  The court also notes that altering the mass and stiffness of the surrounding liner can alter the frequencies of vibration that could be dampened.  The court further discussed resistive attenuation of dampening and reactive attenuation.

Second, the court notes that the patent claims do not discuss how the dampening is to be achieved but states merely limits upon the dampening effect that are subject of the claims.  (As discussed below, this appears to be a failure to teach enablement under 35 USC Section 112.)

Third, the court notes that the patent specification and method claims merely taught that an application of Hooke’s law was to be applied.  Hooke’s law is an equation that describes the relationship between an object’s mass, its stiffness, and the frequency at which the object vibrates.  Hooke’s law is a well understood scientific principle and therefore the patent claims were merely stating that user apply a natural law.  This tracks the Supreme Court’s dicta in Mayo v. Prometheus.  (See my earlier post mentioned above.)  To paraphrase the Court in Mayo, a patent claim can’t be limited to stating: take a specified natural law or scientific principle and now apply it.  

Further, the court applied the test of determining patent eligibility of of claims incorporating natural law.  The test, derived from the Supreme Court’s decisions of Mayo and Alice Corp. Pty. Ltd. v. CLS Bank International, comprises two parts.  Step one is to determine if the claim is directed to application of a natural law, phenomena or abstract idea.  The second step is to determine if the claim further embodies sufficient additional steps to establish some inventive concept, i.e., is the claim directed sufficiently to application elements that are sufficient to ensure that the patent in practice amounts to significantly more than claiming a natural law, phenomena or abstract idea.

The court found that the patent claims were directed to “tuning liners”, i.e., controlling a mass and stiffness of at least one liner to configure the liner to match the relevant frequency or frequencies.

The limitations of the invalidated claim are stated above.  The court stated that the problem was that the solution to achieving the desired result is not subject of the claim.  Further, the court implies that the patent specification merely repeats facts or art previously known in the industry.  The court states:  “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 line to dampen bending mode vibrations.”  

The court states that the patent specification describes the tuning of vibration in terms of the results achieved rather that the particular process by which the result is accomplished.  (I believe this to be the most significant flaw of the patent, i.e., failure to teach enablement.)  The court states explicitly that “though we recognize that AAM may be correct in its assertion the system involved (in the patent) is more complex that just a bare application of Hooke’s law and that other laws of nature may be relevant, that does not render the subject matter patent eligible.  What is missing is any physical structure or step for achieving the claimed result of damping two different types of vibrations.

For what it is worth, one justice dissents, stating that the flaw is failure to teach enablement, i.e., enablement being the patent specification (combined with the drawings), containing sufficient information to teach or enable a persons skilled in the relevant technology to understand the invention and replicate it without undue experimentation.  (The majority of the three justice court panel concedes that the specification leaves the reader with a trial and error methodology.)  The dissenting justice argues that the majority is improperly applying the “natural law” prohibition, and thereby is creating uncertainty, i.e., “validity goulash”.  The dissenting justice makes the point that dependent claims do teach structural limitations that enable achieving the vibration damping standards. 

Therefore it is possible to argue that this failing is one of inadequate patent drafting or disclosure of the improvement by the inventors.   See my March 19, 2019 post Teach Enablement for further discussion on this critical requirement of patents.


Although I have consistently argued that if you have achieved what you believe to be an innovation but do not have the resources to hire an experienced patent attorney, the default position is to file your own provisional application (teaching enablement), then see if your innovation can achieve traction in the market or via investment.  “Don’t do nothing”.  However, to effectively protect intellectual property, you ultimately will need the services of an experienced patent attorney that can draft your patent application and properly claim your invention.  

© David McEwing, 2019