Choice of words can have a significant impact on conveying meaning. Patent drafting is no different. For example, the smallest word such as “a” can significantly change the scope of a construed claim. Patent practitioners must continue to ask, what do I mean by “a.”

In a recent case Salazar v. AT&T Mobility LLC, 64 F.4th 1311 (Fed. Cir. 2023), the Federal Circuit discussed the meaning of “a” in the context of open-ended claims with the transitional phrase “comprising.” In Salazar, the claim phrases at issue read:

1. A communications, command, control and sensing system for communicating with a plurality of external devices comprising:

a microprocessor for generating a plurality of control signals used to operate said system, said microprocessor creating a plurality of reprogrammable communication protocols …

a memory device coupled to said microprocessor configured to store a plurality of parameter sets retrieved by said microprocessor so as to recreate a desired command code set …

said microprocessor generating a communication protocol in response to said user selections ….

At issue was the construction of the articles “a” and “said” followed by the term “microprocessor.” In previous cases, the Federal Circuit explained that the indefinite article “a” means “‘one or more’ in open-ended claims containing the transitional phrase ‘comprising.’” Convolve, Inc. v. Compaq Computer Corp., 812 F.3d 1313, 1321 (Fed. Cir. 2016) (quoting KCJ Corp. v. Kinetic Concepts, Inc., 223 F.3d 1351, 1356 (Fed. Cir. 2000)). “An exception to the general rule that ‘a’ … 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.” Baldwin Graphic Sys., Inc. v. Siebert, Inc., 512 F.3d 1338, 1342-43 (Fed. Cir. 2008). “The subsequent use of [the] definite article[] … ‘said’ in a claim to refer back to the same claim term does not change the general plural rule, but simply reinvokes that non-singular meaning.” Id. at 1342.

In Salazar, the district court construed the claim terms at issue to mean “one or more microprocessors, at least one of which is configured to perform the [recited] generating, creating, retrieving, and generating functions.” Salazar, 64 F.4th at 1314. On appeal, Mr. Salazar held a view that a correct claim construction would encompass one microprocessor capable of performing one claimed function and another microprocessor capable of performing a different claimed function, even if no one microprocessor could perform all of the recited functions. Id. at 1315.

The Federal Circuit, however, agreed with the district court’s claim construction. Id. at 1317. In reaching the decision, the Federal Circuit reasoned:

Although Mr. Salazar insists that the phrase “said microprocessor” “simply reinvokes th[e] non-singular meaning,” … the claim’s use of “said” does not negate what is required by the language that follows “said”: a “microprocessor” that “generat[es],” “creat[es],” and “retriev[es].” As we stated in [another case], “[f]or a dog owner to have ‘a dog that rolls over and fetches sticks,’ it does not suffice that he have two dogs, each able to perform just one of the tasks.” … Here, it does not suffice to have multiple microprocessors, each able to perform just one of the recited functions; the claim language requires at least one microprocessor capable of performing each of the recited functions.

Id. at 1318. Based on the claim construction, the Federal Circuit affirmed the holding of noninfringement.


Salazar shows how a patent drafter’s choice of words, even seemingly small ones, may significantly change the scope of a construed claim. If it’s intended to claim a set of one or more elements (e.g., processors), collectively, jointly, or individually, to perform multiple functions, practitioners are cautioned against relying on the general rule that “a” means “one or more” in an open-ended claim with the transitional phrase “comprising,” when considering how to recite the elements in the claim.

As the outcome in Salazar suggests, depending on how the claim is drafted, using “a” in such instances may result in a construction requiring that all of the multiple functions be performed by a single element.

Expressly spelling out what is intended to be covered by a claim may be a more conservative approach of claim drafting in this context. For example, practitioners may consider expressly reciting, in a claim, “one or more” elements to perform desired functions for broader coverage.