The U.S. Court of Appeals for the Federal Circuit recently upheld a district court’s decision that a preamble stating an intended use for an invention is insufficient to distinguish a patent claim over prior art. Marrin v. Griffin, Case No. 09-1031. (Fed. Cir., Mar. 22, 2010) (Dyk, J.) (Newman, J. dissenting).

In this patent dispute, the district court granted summary judgment that the patent-in-suit, which related to a beverage cup scratch-off label, was invalid because it was anticipated under 35 U.S.C. § 102(b).

On appeal, a panel majority of the Federal Circuit held that the use recited in the preamble, namely that the scratch-off label was “for permitting a user to write thereon without the use of a marking implement” was not to be treated as a claim limitation. In finding that this use statement in the preamble was not limiting, the Court noted that “use descriptions such as this are rarely treated as claim limitations.” The Court further found that “the mere fact that a structural term in the preamble is part of the claim does not mean that the preamble’s statement of purpose or other description is also part of the claim.” The Court pointed out that “[h]ere, the preamble language only added an intended use, namely, that the scratch-off layer may be used for writing.” The Court agreed with the district court’s finding that the patentees had not relied on the preamble language as a limitation during prosecution. The Court also noted that, during prosecution, the patentees “expressly attested that the ‘writing means’ language was not a claim limitation,” thus “they cannot now assert that it was such a limitation.” The Court accordingly affirmed the district court's judgment of invalidity and non-infringement.

In dissent, Judge Newman asserted that “[t]he majority’s excision of the very portion of the claim that distinguishes the invention from the prior art, only to invalidate the claim on the basis of that prior art, is contrary to law.” Judge Newman went on to describe how the patentees distinguished prior art in their patent specification and noted that such differences “are ignored by my colleagues … [the majority] instead engrafts a meaning on the claim that the inventors did not present and the Patent Office did not examine.”

Practice Note: When drafting patent claims, it is important to ensure that elements potentially necessary to distinguish over prior art are recited in the body of the claim, not merely included in the preamble.