United States: Claim Construction: A Hard Pill To Swallow For The Unwary

The process of construing the disputed terms of a patent is a seminal stage in many patent cases. The outcome-determinative nature of a claim construction order leads many parties to stipulate to a judgment of infringement or non-infringement so the disadvantaged party may appeal the unfavorable construction.

A recent claim construction order by the Delaware District Court in Purdue Pharma1 highlights the importance of describing multiple embodiments in an application to obtain a broad claim construction of even seemingly unambiguous claim terms and reminds that statements made during prosecution are imputed to related cases and therefore applicants must be careful to avoid any unduly limiting effects of such statements.

The construction order in Purdue Pharma dealt with several disputed claim terms in U.S. Patent No. 9,675,610 ("the '610 Patent"), directed to a solid controlled-release dosage of a pharmaceutical drug, and U.S. Patent No. 9,750,703 ("the '703 Patent"), directed to an abuse-proof pharmaceutical dosage for oral administration.

At issue, with respect to the '703 patent, was the interpretation of the term "layer encasing the core," with the patentee arguing that the term "layer" means one or more materials, and the defendant arguing that this term refers to a single material. The Court noted that the specification of the '703 patent described an embodiment in which a shell of the dosage form may be formed "by compression coating, molding, spraying one or more layers onto the core" or "dipping one or more layers onto the core." The specification further disclosed that in some embodiments an "optional coat" may be "alternatively or additionally applied as an intermediate layer between the core and the compression coating." Based on these disclosed embodiments, the Court agreed with the patentee's broad construction that the term "layer encasing the core" means "one or more materials enclosing a space or surrounding the core," seemingly inferring from these embodiments that the different coatings may be formed of different materials.

While applicants may be inclined to believe that the meanings of simple terms such as "layer" are readily apparent even to lay persons and therefore should be given broad constructions consistent with their ordinary and customary meanings, the Purdue Pharma case reminds that courts may look to the embodiments described in the application to inform the meaning of even seemingly unambiguous terms. Accordingly, to the extent possible, applicants should describe several different embodiments of any significant claim term. Doing so will give the patentee a greater likelihood of obtaining a broad claim construction, because courts are reluctant to adopt an interpretation of a claim term that would not cover the disclosed embodiments.2

The Purdue Pharma claim construction order also highlights the importance of statements made by counsel during patent examination, even in related cases not before the Court.

The parties' dispute with respect to the '610 patent centered on the meaning of the phrase "remain visible to the naked eye." The claims of the '610 patent are directed to a pharmaceutical dosage that forms a gel when combined with water that can be drawn up into and injected back out of a hypodermic needle. When the gel is injected from the hypodermic needle into water, threads of the gel "remain visible to the naked eye." These visible gel threads prevent the gel from being dispersed or dissolved, which could otherwise allow the gel to be administered parenterally (i.e., other than by oral administration). In this manner, the claimed pharmaceutical dosage is configured to prevent intravenous administration by an abuser of the pharmaceutical.

During prosecution of an application related to the '610 patent, the patentee argued that the claimed dosage form excludes dosage forms that result in threads that "immediately disappear" when injected into water. Based on the patentee's prosecution disclaimer of threads that "immediately disappear," the Court held that the phrase "remain visible to the naked eye" means "can be seen with the naked eye . . .  and do not immediately disappear."

Although the patentee in Purdue Pharma agreed with this construction, applicants must nevertheless be mindful that statements made in a parent application are imputed to the same claim term in a child application. This can be particularly significant if the imputed meaning of the claim term is narrower than the plain and ordinary meaning of the term or if the imputed meaning is not required for patentability. The latter is true, for instance, if the claims in the child application are patentable over the references cited against the claims in the parent application based on a claim term in the child application that is not present in the claims of the parent application.

To avoid the undesirable effects of statements made in a related application, applicants should consider making a statement on the record expressly rejecting the meaning adopted in the related application, or, if possible, adopting a new claim term, which would presumptively carry a different meaning.3

The Purdue Pharma case is just the latest reminder that an application may need to contain multiple embodiments for even seemingly simple terms to be given a broad construction, and that statements made during prosecution have the potential to unduly limit the scope of claims in related cases. With these considerations in mind, applicants are less likely to be subject to an unfavorable claim construction.


1 Purdue Pharma L.P. v. Alvogen Pine Brook LLC, Civil Action No. 15-687-GMS (D. Del 2018).

2 Oatey Co. v. IPS Corporation, 514 F.3d 1271 (Fed. Cir. 2008) ("We normally do not interpret claim terms in a way that excludes embodiments disclosed in the specification. . . . At leas[t] where claims can reasonably [be] interpreted to include a specific embodiment, it is incorrect to construe the claims to exclude that embodiment, absent probative evidence on the contrary.").

3 Kara Tech., Inc. v. Stamps.com, Inc., 582 F.3d 1341, 1347 (Fed. Cir. 2011) (different claim terms in related patents are presumed to carry different meanings).

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