Salazar v. AT&T Mobility: The plurality of “a” in patent prosecution.

Salazar v. AT&T Mobility

By Ted Stueber

Reviewed by Dr. Jon Platt

 A starting point in approaching the complexity and confusion of using the article “a” in patent prosecution is a quote from the Federal Circuit’s case Insituform Techs., Inc. v. CAT Contr., Inc., 99 F.3d 1098, 1106 (Fed. Cir. 1996)): “When the claim language and specification indicate that ‘a’ means one and only one, it is appropriate to construe it as such even in the context of an open-ended ‘comprising’ claim.” 

Translated out of legalese, the quote states the article “a” in the context of an open-ended “comprising” claim means one or more, or at least one, but when the language of the claim indicates that the article “a” should mean only one it would be appropriate for the court to interpret the article “a” to be only one. This approach has been followed in subsequent cases, such as KCJ Corp. v. Kinetic Concepts, Inc., 223 F.3d 1351 (Fed. Cir. 2000), Baldwin Graphic Sys., Inc. v. Siebert, Inc., 512 F.3d 1338 (Fed. Cir. 2008), Harari v. Lee, 656 F.3d 1331 (Fed. Cir. 2011), and Azurity Pharms., Inc. v. Alkem Lab’ys Ltd, No. CV 19-2100-LPS, 2021 WL 5332406 (D. Del. Nov. 16, 2021).

However, the Federal Circuit clarified its point of view in Aug. Tech. Corp. v. Camtek, Ltd., 655 F.3d 1278, 1282 (Fed. Cir. 2011), stating that construing “a wafer” as “a plurality of wafers” would render “a wafer” superfluous since a claim interpretation that gives life to all the terms is better than one that makes certain terms redundant. Basically, stating that the article “a” could be construed to mean one or more in that particular case, but the way the claim was worded it would not make sense to interpret “a” as one or more and therefore should be interpreted as singular.

In Salazar v. AT&T Mobility, a Federal Circuit opinion issued in April, a patentee obtained a patent (US Patent 5,802,467, “the ‘467 patent”) on a system for wireless and wired communications including command control and sensing for two-way communication of sound voice and data, with any appliance or apparatus capable of transmitting and or receiving compatible sound voice and data signals. The patentee filed an infringement action against AT&T and other cellphone companies (collectively, “AT&T”), who prevailed at trial on a defense of noninfringement. The claim at issue was claim 1 of patent ‘467:

               Salazar, the patentee, contented that the “a microprocessor” for “generating,” “creating,” “retrieving,” and “generating,” (the processes highlighted in the claim above) should be interpreted as one or more microprocessors that do all the recited functions, with claim covering the possibility that different microprocessors could perform different of the functions. AT&T argued that the claim should be interpreted as requiring one microprocessor that is capable of performing all of the recited functions, as opposed to a system of microprocessors, working together to complete all of the functions.

The Federal Circuit upheld the jury’s finding of noninfringement. The court concluded that the claim term “a microprocessor” does not require there be only one microprocessor, but the subsequent limitations referring back to “said microprocessor” require that at least one microprocessor be capable of performing each of the claimed functions. In its ruling, the court gave an example using a dog. The court stated for 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.”

This result complicates patent prosecution, and litigation. Using the article “a” seems to be interpreted more subjectively by the court. Therefore, patent attorneys and patent agents must prioritize clarity in writing of claims to unambiguously provide that different functions need not be performed by the same device.

It is important to note that this case does not hold that “said” changes the plurality of the thing “said” is referring back to. “Said” still refers back to the plurality of the word it is referring back to, but if the court determines that pervious word is singular, “said” refers to something singular. Therefore, by using “a” and “said” combination, without being particular to the plurality of “a”, a patent attorney would be gambling that the court would interpret the article “a” the same way that the patent attorney intended.

One way a patent attorney could be more specific in the writing of their claims is to be their own lexicographer. Somewhere in the specification, define the article “a” to be one or more, or define the actual components of the invention to be one or more. But there is a danger in relying on a statement in the specification to control interpretation of the claims.

Another way a patent attorney or patent agent could be more specific on the plurality of the article “a” is to use the phrase “one or more” as an alternative to “a” or “an.” But merely making an explicit reference to “one or more” may not provide the requisite clarity -- in the dog example cited above, “one or more dogs that roll over and fetch sticks” still might be interpreted as requiring a dog that performs both the rolling over and the fetching.

Another approach would be to define an intermediate recitation that includes the one or more items. In the dog example the recitation might be changed to “a dog pack that includes one or more dogs, wherein the dog pack is capable of performing both rolling over and fetching sticks.” This leaves open the option that the two functions are performed either by the same dog, or by different dogs. In claim 1 of the ‘467 patent, “a microprocessor” (or “one or more microprocessors”) may be recited as included in “a processor subsystem” that in turn performs the specified functions.

Salazar v. AT&T Mobility, while not breaking any significant new ground, underscores the importance of getting a qualified patent attorney involved early in the preparation and prosecution of patent applications. Patent law has its own rules and conventions of language usage and interpretation, some of which run contrary to how writing in a non-patent context is approached. Expertise in this area of the law can make all the difference between an enforceable patent and one which has claims that as a practical matter are worthless.

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