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Is PTAB dropping the ball on defining who is a PHOSITA?

Under the current patent law, an inventor cannot obtain a patent for an invention that is obvious to a “person having ordinary skill in the art” (PHOSITA). However, courts often struggle with whether the relevant person should be identified based on the invention disclosed in the specification or the invention claimed. The Patent Trial and Appeal Board (PTAB) has for a number of years now adopted the former approach, stemming from the case of Axonics Modulation Technologies, Inc. v. Medtronic, Inc., IPR2020-00715 (PTAB Sep. 13, 2021).

The inventors, Drs. Schmidt and Tanagho, discovered that stimulation of the sacral nerves could alleviate various pelvic floor disorders and subsequently obtained U.S. Patent No. 8,036,756, which relates to an implantable medical electrical lead for stimulating a bundle of sacral nerve fibers.

Axonics filed a petition for inter partes review, asserting that certain claims of the ’756 patent were obvious in light of prior references: Young, Gerber, and two others. The Patent Owner argued that a correctly-defined PHOSITA would not have been motivated to combine Young with Gerber or the other references.

The Petitioner defined a PHOSITA as someone with experience in implantable medical devices (e.g., a bachelor’s degree in biomedical engineering and relevant research experience). The Patent Owner, however, defined a PHOSITA as a specialist in sacral neuromodulation, potentially a physician with specific experience in this field, or an expert in implantable medical lead design with sacral neuromodulation experience, working closely with such a physician. The Patent Owner criticized the Petitioner’s definition for not requiring knowledge of sacral anatomy or neuromodulation, which they argued was necessary based on the context of the ’756 patent.

The Petitioner countered that the challenged claims did not specify sacral anatomy or neuromodulation, and thus a PHOSITA did not need such experience to understand and practice the invention.

The Board sided with the Patent Owner, reasoning that the specification of the ’756 patent defined the field of the invention as medical electrical leads for sacral neuromodulation and included descriptions related to sacral anatomy. They found that the claims’ lack of specific mention of sacral anatomy or neuromodulation did not override the specification’s explicit field of invention.

According to the Board, the claims’ purpose is to define the boundary of the patent monopoly, not the subject matter of the patent. Therefore, the Board determined that a PHOSITA would have experience in developing medical leads for sacral neuromodulation, agreeing with the Patent Owner that such a PHOSITA would have had no reason to combine Young with Gerber, making the claims non-obvious.

Notably in this case, the Patent Owner advocated for a higher standard for PHOSITA than what the Petitioner proposed, with the Petitioner suggesting a generalist and the Patent Owner suggesting a specialist. This is not typical. Patent Owners often argue for a more liberal standard for PHOSITA since higher-skill experts are rather expensive, and Patent Owner budgets often pale in comparison to the party accused of patent infringement.

This atypical stance in Axonics however, was perhaps due to the nature of the references cited. Young was about electrical stimulation for facial pain, related to general neurosurgery rather than sacral neuromodulation. Gerber, while mentioning sacral nerves, did not relate specifically to sacral neuromodulation.

The Board acknowledged that the references collectively disclosed every limitation of the independent claim but agreed with the Patent Owner that there would have been no motivation to combine the references. They found that skilled artisans in sacral neuromodulation would not have looked to general neurosurgery for solutions. The Board posited that a PHOSITA might find it obvious to combine references if the ’756 patent disclosed simpler mechanical technologies, but the technologies involved complex medical devices for neurostimulation.

In defining PHOSITA, the Board declined to focus solely on the claimed invention. The Petitioner argued that the claims did not mention sacral anatomy or neuromodulation and that the ’756 patent described uses beyond sacral anatomy. However, the Board found that the specification’s description of the field of invention should prevail, emphasizing that the claims define the boundary of the patent monopoly but not the invention's subject matter.

It should be noted that the United States Patent and Trademark Office (USPTO) examines patent applications by comparing the prior art to the claims, not the specification. The Manual of Patent Examining Procedure (MPEP) directs examiners to cover both the claimed subject matter and the disclosed features expected to be claimed, with a focus on the claims. Although the MPEP does not explicitly state whether PHOSITA should reflect the specification or the claims, it always points to the claims for obviousness analyses.

The Board’s choice to focus on the specification, particularly when it defines a narrow field of invention, contradicts the MPEP’s guidance. The Board’s approach raises other significant concerns as well. Ignoring the claims when defining PHOSITA could allow an inventor to narrowly define the field of invention while claiming the invention broadly, potentially stifling innovation in more sophisticated fields where the invention might be obvious to a skilled artisan.

There is therefore an argument to be made for considering the claim language in defining PHOSITA, regardless of the stated field of the invention. If the invention is claimed broadly, then PHOSITA’s expertise should reflect that breadth. This approach ensures that if the invention is obvious to a skilled artisan in any relevant field, the claims are not patentable.The claims define the boundary of the patent monopoly, and since obviousness should be tested against these boundaries, a PHOSITA should be one with relevant expertise to the claimed invention even if that is broader or narrower than the stated field of the invention. This would also maintain the balance between protecting genuine innovation and preventing overly broad claims that could hinder technological progress.


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