The paper trail in a patent application can save it from invalidation. KAKEN v. IANCU

A patent is a set of exclusive rights granted to the inventor of a new invention. The steps that an inventor follows to gain a patent is referred to as patent prosecution. Patent prosecution is a cooperative, interactive process in which the patent applicant and the applicant’s attorney work with the staff and the United States Patent and Trademark Office to address various concerns regarding an invention’s patentability.

The patent prosecution process typically begins with an inventor choosing a patent attorney to assist them. The patent attorney will review the invention and search the prior art to determine the likelihood a patent can be obtained. The patent attorney then files a patent application with the United States Patent and Trademark Office. The United States Patent and Trademark Office will assign an examining attorney to review the patent application. The patent applicant’s attorney and the examining attorney will communicate regularly during the patent examination process until the patent is granted or the examining attorney refuses to issue a patent.

The patent examination process and the communication that the patent applicant has with the patent examiner must be carefully crafted. This is because all communications during patent prosecution are preserved after the patent is granted. What a patent applicant makes a statement during the examination of the patent application, it cannot later make an inconsistent statement. Judicial estoppel prevents a patent applicant from making one argument during prosecution and an opposite argument afterwards.

The opposite is also true. If the patent examiner raises an objection during patent prosecution and the applicant’s attorney overcomes that objection, that becomes part of the record as well. Prosecution history is strong evidence of what a skilled artisan would have understood disputed claim language to mean. This means that if the same issues are later raised in an attempt to invalidate the patent, the prosecution history can save the patent.

KAKEN PHARMACEUTICAL CO., LTD. v. IANCU, 18-2232 (C.A.F.C. 2018) is an example of a case where prosecution history played an important role in preserving a patent. The plaintiff in this case owns U.S. Patent No. 7,214,506 which describes and claims methods for topically treating fungal infections in human nails. In November 2016 Acrux Limited sought an inter partes review of all claims of the ’506 patent. The Patent Trial and Appeal Board determined that all claims of the ’506 patent were unpatentable for obviousness. The plaintiff appealed the Board’s decision to the Court of Appeal for the Federal Circuit. Acrux did not want to proceed, so the Board’s decision was defended by IANCU as the director of the US Patent Office.

The plaintiff’s appeal focused on the Board’s interpretation of one of the claims in the ’506 patent. Specifically, the plaintiff challenges the Board’s construction of “treating a subject having onychomycosis.” Onychomycosis, also known as tinea unguium, is a fungal infection of the nail. The prior art cited in the inter partes review taught the treatment of onychomycosis on skin. The Board interpreted skin to include the areas around and under a nail, because a nail grows out of skin. The Federal Circuit held, that the Board’s claim construction is unreasonable given the specification and prosecution history of the ‘506 patent.

The Federal Circuit found that the prosecution history included, statements made by Kaken to overcome a rejection and the examiner’s statements explaining withdrawal of the rejection based on those statements. Kaken’s statements provided decisive support for limiting the claim phrase at issue to a nail plate penetrating treatment of an infection inside or under the nail plate. The prior art taught the treatment of onychomycosis on skin on the surface of a person, the prosecution history demonstrated that Kaken’s invention treated onychomycosis by penetrating a nail and treating the tissue under the nail.

While Kaken’s statement during patent prosecution narrowed the scope of the patent, ultimately it saved the patent from invalidation. The Federal Circuit remanded the matter to the Board for reconsideration consistent with the narrower interpretation of the claim.

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