How Many Microprocessors is "a Microprocessor"?
How should the indefinite article “a” or “an” in a claim be construed? Should it be construed to mean “one” or “one or more”? For example, if a claim recites “a microprocessor” followed by a list of its functions, should the claim be construed as requiring a single microprocessor or one or more processors that perform the recited functions? If the claim covers multiple microprocessors, must at least one of them perform all of the recited functions, or is it sufficient for the microprocessors to perform the recited functions collectively, even if no single microprocessor performs all of them?
The Court of Appeals of the Federal Circuit (“CAFC”) addressed these questions in Salazar v. AT&T Mobility LLC,[1] where it affirmed a district court’s judgment of noninfringement. The patent-in-suit is Salazar’s U.S. Patent No. 5,802,467 directed to wireless and wired communications. The asserted claims recited “a microprocessor for generating . . . , said microprocessor creating . . . , a plurality of parameter sets retrieved by said microprocessor . . . , [and] said microprocessor generating . . . .” At claim construction, Salazar argued that the above limitations require one or more microprocessors, any of which may be capable of performing each of the recited functions.
The district court disagreed and construed the limitations to mean “one or more microprocessors, at least one of which is configured to perform the generating, creating, retrieving, and generating functions.” The district court reasoned that the limitations not only provided certain functions that “said microprocessor” must necessarily perform, but also provided the structural relationship between “said microprocessor” and other structural elements. Thus, the district court concluded, the limitations require at least one microprocessor that satisfies all the recited functions.
On appeal, the CAFC focused on the proper construction of the articles “a” and “said.” Relying on its own precedent, the CAFC explained the general rule that “a” means “one or more in open-ended claims containing the transitional phrase comprising[,]” except where “the language of the claims themselves, the specification, or the prosecution history necessitate a departure from the rule.” Furthermore, “said” indicates “a reference back to the previously claimed term” and “does not change the general plural rule, but simply reinvokes that non-singular meaning.” In other words, the Court said that “a” means “one or more” except when it doesn’t; there is no “bright line” rule.
For example, the CAFC noted that in In re Varma,[2] it construed the limitation, “a statistical analysis request corresponding to two or more selected investments,” as requiring at least one request that corresponds to the two or more selected investments. This is because “a request” is a singular term that “correspond[s] to two or more selected investments,” and the term “a” cannot serve to negate what is required by the language that follows. Similarly, “[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.” Consequently, no matter the amount or variety of requests, the claim requires at least one request that itself corresponds to at least two investments.
Based on this precedent, the CAFC agreed with the district court that although “a microprocessor” does not necessarily require a single microprocessor, the subsequent limitations referring back to “said microprocessor” require at least one microprocessor that performs each of the recited functions, and not one or more microprocessors that collectively perform all of the functions.
Referring to the district court’s interpretation that the indefinite article “a” means “one or more,” Salazar argued that the phrase “one or more” should be understood to mean “any one of the one or more” when referring to the later recited functions of “said microprocessor.” Salazar’s position relied on the statement that the phrase “said microprocessor” simply reinvokes the non-singular meaning. Regardless of Salazar’s position, the CAFC rebutted and reaffirmed that the use of the term “said” in the limitations cannot serve to negate what is required by the language that follows the term “said.” The Court explained that it does not suffice to have multiple microprocessors, each microprocessor able to perform just one of the “generating, creating, retrieving, and generating” recited functions that follow “said microprocessor.”
Consequently, no matter the amount of microprocessors, the claim language of “a microprocessor” and “said microprocessor” used in Salazar’s patent requires at least one microprocessor to be capable of performing each of the recited functions. Therefore, at least one microprocessor must be capable of performing the generating, creating, retrieving, and generating functions recited in the claim language. The CAFC thus affirmed the district court’s judgment of noninfringement.
To summarize, in the case of Salazar v. AT&T Mobility LLC,1 the patent owner Salazar failed to successfully enforce the patent because the specification and claim language did not support the construction needed to establish infringement. In this case, if the claim language had covered a product in which multiple microprocessors collectively perform the recited functions, even if no single microprocessor performs all the recited functions, the claims may have been construed favorably for Salazar.
For example, if the patent draftsman replaced “a microprocessor” with “one or more microprocessors” and replaced “said processor” with “any of the one or more microprocessors”, the claim language may have covered both a single microprocessor performing all the following recited functions and multiple microprocessors collectively performing all the following recited functions, even if no single microprocessor performs all the following recited functions.
Alternatively, if the specification included appropriate definitions, the claim language may have been construed more favorably for Salazar. For example, the patent drafter may have included a statement in the specification such as “as discussed herein, reference to a single “microprocessor” may mean one or more processors that individually or collectively perform all the described functions.” It is advisable that when using indefinite articles “a” and “an,” a patent drafter state appropriate definitions in the specification regarding whether “a” and “an” mean “one” or “one or more,” especially if followed by a list of its functions.
