Takeaway: Though not cited in In re Skvorecz, the leading case on the meaning of EACH is ResQNet.com, Inc. v. Lansa, Inc., 346 F.3d 1374 (Fed. Cir. 2003). According to ResqNet, EACH OF A PLURALITY OF Xes means SOME OF THE Xes, where EACH X means ALL Xes. To be safe, reinforce these meanings by using words like "some," "all," and "every" when describing the feature in the spec.
Digging Deeper: Why was I surprised at the Skvorecz conclusion that "each" means "every"? In a word: "comprising." That is, doesn't black letter patent law say that when "comprising" is used, additional elements are irrelevant? In the Skvorecz case, isn't it irrelevant whether or not additional legs have X, as long as the claimed "plurality of legs" have X?
Actually, it's more nuanced than that. A device including unclaimed elements still infringes when "comprising" is used as the transition. Crystal Semiconductor Corp. v. TriTech Microelectronics Int'l, Inc., 246 F.3d 1336, 1347 (Fed.Cir. 2001). A device including additional instances of a claimed element does not escape infringement when the article "a" is used, absent a clear intent to limit the article. See KCJ Corp. v. Kinetic Concepts, Inc., 223 F.3d 1351, 1356 (Fed. Cir. 2000).
ResQNet, Inc. v. Lansa, Inc. addresses additional instances of a claimed element introduced by the article "each." ResQNet interpreted two similar claims that used "each," with opposite results.
The ResQNet Court found EACH = EVERY in this claim:
means for receiving information to be displayed as a first image on a screen;The Court said the claim language itself dictated EACH = EVERY: "This [claim] language shows that the claimed algorithm evaluates attributes of each (and every) field in the information to be displayed, i.e., the first image."
means for processing said information to generate a screen identification (“ID”) from said first image, said ID being generated as a function of the number, location, and length of each field in said first image ...
Yet the ResQNet Court found EACH <> EVERY in this other claim:
means for identifying, based upon a position, length and type of each of a plurality of fields, a particular screen to be displayed to said user;See the difference? It's EACH OF A PLURALITY OF FIELDS versus EACH FIELD. The Court focused exclusively on "plurality":
Claim 1 of the ’608 patent recites “each of a plurality of fields,” which does not carry the same meaning as “every field.” Rather, the recitation of “plurality” suggests the use of “at least two.” ... While “at least two” may mean “every” under some circumstances, the two terms are not synonymous. In sum, “each of a plurality of fields” means “each of at least two fields.”At first I didn't see the difference between the two claims, because I was *inferring* a plurality when I read "each field in said first image." But in fact, this claim never says plurality of fields, and is in fact agnostic as to how many fields there are. Once I realized that, the Court's construction made more sense.
Note that the Court bolstered its interpretations by referring to the specification. For the EACH = EVERY claim, the Court found that:
The specification confirms the “all fields” requirement in the ’961 claim: "In describing the determination of the screen ID, the specification provides that “the particular screen [is identified] by its layout, fields, etc." and " ... From the display buffer, the program derives the following information: ... b) type of each field ... With the words “each field” and “fields,” this passage suggests that characteristics of all, not just some, fields are inputs into the algorithm. Nowhere does the specification suggest otherwise.Do these passages really confirm that EACH = EVERY? To me, these passages shed no light at all, one way or another.
Contrast this with the spec for the EACH <> EVERY claim. The Court found that:
The ‘608 specification confirms this meaning of the claim language. In the only portion specifically addressing whether the algorithm employs all or some fields, the specification notes that “the personal computer analyzes the screen with respect to the location of particular fields.” This passage suggests that the PC selects certain fields – potentially a subset of all fields – for analysis.I do agree that "particular fields" suggests not every field, so that the '608 spec supports EACH <> EVERY.
Would a different result be reached with a different description in the spec? Because I don't buy the Court's single-minded focus on the word PLURALITY in the phrase "each of a plurality of fields." After all, the word EACH is present too, and the Court didn't satisfactorily explain to me why PLURALITY negates EACH.