Symbol Technologies, Inc. v. Janam Tech. LLC
605 F.Supp.2d 618 (D.Del. 2009)
Civil Action No. 08-340-JJF
The claim term at issue was "power." The method claim recited:
7. A method for facilitating power shutdown protocol of a computing device, comprising the steps of:
... using a seconary cell as a backup portable power supply;
using a boost circuit to increase the power of the secondary cell ...
In the field of electronics, "power" is a term of art, with a specific meaning: voltage multiplied by current. The accused infringer advocated for this construction, but the patentee wanted a more informal definition of power: voltage. According to the patentee, a POSITA would understand that the inventors intended for "power" to mean "voltage" because the specification did not explicitly adopt the ordinary meaning, and the specification also used the two terms loosely and interchangeably.
A magistrate judge originally assigned to do claim construction adopted the patentee's interpretation. But when the accused infringer objected, the court reversed and adopted the plain and ordinary meaning to a POSITA: voltage multiplied by current.
The court found that the spec neither explicitly adopted nor explicitly rejected the ordinary meaning, and the patentee's own expert admitted that some portions of the spec did use the ordinary meaning. The court also rejected the idea that "power" and "voltage" were used interchangeably in the spec. As support for this argument, the patentee pointed to various passages that described the power supply circuit solely in terms of volts (e.g., "5 volt power supply circuit"). But the court found that other portions of the spec clarified this usage by describing the circuit in terms of a combination of power and voltage (e.g. "steady 5 volt DC [direct current] power"). Thus, the spec when read as a whole consistently referred to the circuit's power output as a combination of both voltage and current.
My two cents: Is there something to be said for using terms inconsistently in your spec? Perhaps if you do this creatively and carefully, it gives you more options later in arguing claim construction. It didn't help the patentee in this case, but that alone doesn't make it a bad idea. After all, the patentee did convince the magistrate judge, and it's entirely possible that a different district court judge would have agreed.
As a patent prosecutor rather than litigator, I'm inclined to be consistent rather than inconsistent. When I'm drafting a spec and find that inventors have used terms inconsistently, I try to figure out what the inventors really meant in each instance, then I make my usage consistent. But perhaps a litigator would prefer a spec that was somewhat inconsistent and thus gave more leeway in claim construction. I'm guessing the patentee here wouldn't have had a case of infringement at all under the ordinary meaning of power, and that's why the patentee came up with this creative line of argument.
I haven't fully thought through this, so I'm not ready to advocate for intentional inconsistency in how claim terms are used in the spec. But I do think it's a valuable exercise to occasionally take off the prosecutor hat and put on the litigator hat.