Prosecution history can define the meaning of patent claims. PMC v. APPLE

A patent is a set of exclusive rights granted to the inventor of an invention. To obtain a patent in the United States an inventor must file a patent application with the United States Patent and Trademark Office. The patent application is reviewed by a patent examiner at the United States Patent and Trademark Office to ensure that the invention described in the patent application meets all the criteria for patent protection. If the patent application meets all the criteria for patentability then the inventor will be granted a patent on the invention.

After a patent is granted it is not immune from attack. Inter partes review is a trial proceeding conducted at the Patent Trial and Appeal Board to review the patentability of one or more claims in a patent only on a ground that could be raised under §§ 102 or 103, and only on the basis of prior art consisting of patents or printed publications. The inventor and the patent examiner do their best to consider all the relevant prior during the patent application process, but sometimes relevant prior art is overlooked. If a member of the public discovers a piece of prior art which anticipates a patent which has been granted they may request an inter partes review of the patent. An inter partes review can result in invalidation of some or all of the claims of a patent.

A patent is made up of several different sections. The claims section of a patent defines what a patent protects. During inter partes review the claims of the patent are compared to the prior art. However words used in the patent claims can have meanings that differ from the common understanding of the same words. The meaning of a word used in a claim, as understood by persons of skill in the art, is often not immediately apparent, and patentees frequently use terms idiosyncratically. The task of claim construction requires examination of all the relevant sources of meaning in the patent record with great care, the better to guarantee the claim’s true meaning is determined. When construing claim terms intrinsic evidence, including the claims themselves, the specification, and the prosecution history of the patent, is relied on. The prosecution history of a patent is important because the repeated and consistent remarks during prosecution can define a claim term by demonstrating how the inventor understood the invention.

PERSONALIZED MEDIA COMMUNICATIONS, LLC, v. APPLE INC., 2018-1936 (C.A.F.C. 2020) is a case where the prosecution history played a key role in defining the meaning of patent claims. PMC owns U.S. Patent No. 8,191,091 which is directed to methods for enhancing broadcast communications by embedding digital signals in the communications. The specification of the patent discloses a number of embodiment that include analog broadcast signals with embedded digital signals.

In March 2016, Apple Inc. filed a petition requesting inter partes review of claims of the ’091 patent. The Patent Trial and Appeal Board instituted an inter partes review in September 2016. In June 2017, the Board issued a final written decision holding the challenged claims anticipated and obvious. In its decision the board focused on the similarities between analog scrambling and digital encryption. The Board found that because analog scrambling was well known in the prior art, digital encryption was also.

PMC appealed to the Court of Appeals for the Federal Circuit. The Federal Circuit focused on whether the broadest
reasonable interpretation of the term, “encrypted digital information transmission including encrypted information”, is limited to digital information or can also include analog information. The Federal Circuit noted that during prosecution, the applicant repeatedly and consistently voiced its position that encryption and decryption require a digital process in the context of the ’091 patent. In a claims amendment the applicant asserted that the amended claims should be allowed because the prior art “does not teach the encryption of an entire digital signal transmission.”

Based on PMC’s statements made during prosecution of the patent the Federal Circuit reversed the Board’s decision invalidating the majority of the ’091 patent claims.

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