On June 30, the U.S. Court of Appeals for the Federal Circuit (CAFC) issued a precedential decision regarding transitional phrase claim construction, reversing the decision of the Patent Trial and Appeal Board (PTAB) in Eye Therapies, LLC. v. Slayback Pharma, LLC. The PTAB had previously ruled the claims of U.S. Patent No. 8,293,742 (the '742 patent) unpatentable as obvious in a inter partes review brought by Slayback. During the inter partes review, the parties had disagreed on the construction of the transitional phrase "consisting essentially of" in the '742 patent. The Court found that the Board had incorrectly applied the conventional open construction of the transitional phrase, which was at odds with the prosecution record. This demonstrates how prosecution history can alter a phrase's typical meaning.
In conventional claim construction, the transitional phrase "comprising" is inclusive or open-ended and does not exclude additional unrecited claim elements or method steps not specifically recited in the claim. However, "consisting of" excludes any element, step, or ingredient not specifically recited in the claim. Typically, "consisting essentially of" limits the scope of a claim to the recited materials or steps and those that do not materially affect the basic and novel characteristics of the claimed invention. The claims at issue in the '742 patent were:
1. A method for reducing eye redness consisting essentially of administering brimonidine to a patient having an ocular condition, wherein brimonidine is present at a concentration between about 0.001% weight by volume and about 0.05% weight by volume.
3. A method for reducing eye redness consisting essentially of topically administering to a patient having an ocular condition a composition consisting essentially of brimonidine into ocular tissue, wherein pH of said composition is between about 5.5 and about 6.5, wherein said brimonidine concentration is between about 0.001% and about 0.025% weight by volume and wherein said composition is formulated as an ocular drop.
In the inter partes review, the PTAB had found the claims obvious by interpreting "consisting essentially of" in the conventional way, allowing for the possibility of other active ingredients. The CAFC determined that this was incorrect due to the meaning of "consisting essentially of" established during prosecution.
During prosecution of the '742 patent, the examiner rejected previous versions of the claims that used the transitional phrase "comprising" instead of "consisting essentially of." The applicant amended "comprising" to "consisting essentially of" in response to the examiner finding that the claims with "comprising" were anticipated by U.S. Patent No. 6,242,442 (Dean), which disclosed the administration of brimonidine and another active ingredient, brinzolamide. The applicant argued during prosecution that Dean required brinzolamide as an active ingredient in addition to brimonidine, and that the amended claims specifically did not require the use of any other active ingredients in addition to brimonidine. Interpreting "consisting essentially of" according to the meaning developed during prosecution and determining that the claims did not involve the use of any other active ingredients, the examiner allowed the amended claims. Thus, the prosecution history had established that "consisting essentially of brimonidine" did not involve the use of other active ingredients, such as brinzolamide, which conflicted with the conventional interpretation of the phrase.
Therefore, the CAFC reversed the Board's claim construction, noting that the obviousness analysis was flawed because the PTAB had applied an erroneous claim construction, finding that the Board did not consider whether a person of ordinary skill in the art, in view of the prior art, would have been motivated to use a method with the meaning of "consisting essentially of" established during prosecution. The Court concluded that the appropriate action, as is the case in many others involving a reversal of a PTAB claim construction, was to vacate the Board's decision and remand the matter to the Board for further proceedings using the corrected claim construction determined by the CAFC.
This precedential ruling shows how a patent's prosecution history can affect the interpretation of words and phrases, including well established conventional interpretations of common transitional phrases. This highlights the weight given to meanings and conclusions developed during prosecution, and how an applicant's arguments and admissions during prosecution can affect interpretation during prosecution and beyond.
The decision is available here.
The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.
