Who has the burden of proof in a dispute over obviousness? IN RE: MEZA

A patent is a government granted monopoly on an invention for a limited period of time. A patent grants its owner the exclusive right to make, use, sell and import an invention within the country that granted the patent. To be granted a patent in the United States an inventor must file a patent application with the United States Patent and Trademark Office. The patent application must meet many requirements to be granted. The most important requirements are that the invention is new, useful and not obvious. The patent law definition of obviousness is not the same as the dictionary definition.

Whether an invention is obvious under patent law depends on the prior art and the knowledge of an ordinary person skilled in the area of technology to which the invention relates. To be obvious every aspect of an invention must be described in the prior art or would have been obvious to a person having ordinary skill in the art. Prior art is any public published information. Patents and patent applications are the most commonly cited forms of prior art, however research papers and sales brochures can also qualify as prior art. During the patent application process the United States Patent and Trademark Office will review publications world wide for relevant pieces of prior art.

When examining patent claims, the initial burden rests with the patent examiner to set out a prima facie case that the claims at issue are obvious over the prior art. The burden then shifts to the applicant to produce evidence or argument supporting patentability. The examiner weighs the prima facie evidence against the rebuttal evidence to determine whether the entirety of the evidentiary record supports a finding of obviousness by a preponderance of the evidence.

A case which touches upon the issue of burden of proof in a patent application is IN RE: MEZA 2018-2219 (C.A.F.C. 2019). Meza filed a patent application for a pump which removes water from pool covers. Pools are frequently covered in the winter, pumps can be damaged by ice, so Meza’s invention included a temperature sensor to cycle the pump when the temperature of the liquid being pumped falls below freezing. The cycling warms ups the liquid enough that it will not freeze inside the pump. Meza’s invention also included a sensor which would stop the pump is no water was present.

The patent examiner assigned to Meza’s patent application found two pieces of prior art which, when combined described Meza’s invention. A patent by Mayleben described a pump with a liquid level sensor and a temperature sensor that would stop the pump if the pump gets too hot. A patent application by Leone describes a pump with a temperature sensor which cycles the pump to prevent the liquid from freezing inside the pump. The patent examiner issued a final rejection of the patent application based on the combination of these two pieces of prior art.

Meza disputed the patent examiner’s final rejection on the basis that in the Mayleben reference the fluid level sensor and the temperature sensor acted independently. Meza appealed the examiner’s rejection to the Patent Trial and Appeal Board, raising the same arguments made to the examiner. The Board sided with the examiner and Meza appealed to the Court of Appeals for the Federal Circuit.

One of the points Meza argued on appeal was that the Board improperly shifted the burden of proof to establish non-obviousness by asking Meza to explain why Mayleben’s pump would not work as claimed with the addition of Leone’s temperature-sensing and cycling functionality. The Federal Circuit affirmed the Board’s decision. The Federal Circuit found that Meza never explained why Leone’s separate external temperature sensing and cycling
functionality would not work with Mayleben’s pump. Based on that lack of rebuttal the Federal Circuit found no reversible error on the part of the Board.

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