An Indefinite Article "A" Or "An" Means "One Or More"

In Baldwin Graphic Systems v. Siebert (No. 07-1262, January 15, 2008), a Federal Circuit panel reaffirms that an indefinite article “a” or “an” carries the meaning of “one or more” in open-ended claims containing the transitional phrase “comprising.” At issue is a district court’s claim construction that the term “a pre-soaked fabric roll” means “a single pre-soaked fabric roll.” In reversing the district court, the Federal Circuit concludes “[t]hat ‘a’ or ‘an’ can mean ‘one or more’ is best described as a rule, rather than merely as a presumption or even a convention.” The exceptions to this rule are extremely limited; a patentee must evince a clear intent to limit ”a” or “an” to “one”.

The panel also notes that “[a]n exception to the general rule that ‘a’ or ‘an’ means more than one only arises where the language of the claims themselves, the specification, or the prosecution history necessitate a departure from the rule.” The subsequent use of the definite articles “the” or “said” in a claim to refer back to the same claim term is not deemed to change the general plural rule, but simply reinvokes that non-singular meaning.