Two issues arise: claim construction, and assertion against which product features.

It only takes infringement of a single claim for a patent assertion to succeed. Damages are not additive by number of claims, unless there are different claim types, such as process and apparatus, and, even then, a case has to be made for it.

Overreaching assertion includes dipping down towards the prior art. A current Patent Hawk matter involves possible assertion against multiple product features. While product feature 1 is a clean hit, novelty assured, the natural inclination is try to widen the infringement umbrella. Product feature 2 could readily be read to fall within claim scope, but upon critical analysis, while not itself a prior art feature, it does appear a descendant of a prior art feature. Reaching halfway down to claim infringement lets the defense try to climb halfway up to argue invalidity. Better pinpoint infringement than risking encroachment into the land of Obzilla. Asserting just against feature 1 does not necessarily alter claim construction. By not asserting against feature 2, the gap between prior art and claimed novelty remains intact.

A plaintiff not knowing the prior art to a goodly degree is both stupid and common. Head-in-the-sand optimistic is no way to begin patent litigation.

Any assertion that relies upon doctrine of equivalents (DOE) is in for heavy sledding if prior art was overcome during prosecution. Festo prosecution estoppel is severe. Outrageously, the CAFC recently ruled, in Honeywell v. Hamilton Sundstrand, that merely rewriting a dependent claim in independent form triggers presumptive surrender of DOE.

[Such a presumption can only be rebutted] by demonstrating that (1) "the alleged equivalent would have been unforeseeable at the time of the narrowing amendment," or (2) "the rationale underlying the narrowing amendment bore no more than a tangential relation to the equivalent in question," or (3) "that there was 'some other reason' suggesting that the patentee could not reasonably have been expected to have described the alleged equivalent." Id. at *14 (quoting Festo IX, 344 F.3d at 1369).

The temptation to widen the infringement umbrella through broad claim construction is best resisted. One aspect is that enablement has become a harsh stricture, as the recent Sitrick v. Dreamworks demonstrated.

Besides the recent trend by courts to be unforgiving to patent holders in claim construction, a better tack may be to exercise some patience. Reissue, while not allowing broadening claims, can improve claim scope with regard to infringement. And, an asserted patent that gets shot down on non-infringement does not often come back for another round against anyone. Taint lingers. Better to wait a few years and see if a tighter infringement fit comes around than to stretch so far as to fall.

The difference between singular and plural is a banana peel of claim construction, as the court can't count. Hyperphase v. Google is one recent case, Baldwin Graphic Systems v. Siebert another:

"[T]his court has repeatedly emphasized that an indefinite article 'a' or 'an' in patent parlance carries the meaning of 'one or more' in open-ended claims containing the transitional phrase 'comprising.'" KJC Corp. v. Kinetic Concepts, Inc., 223 F.3d 1351, 1356 (Fed. Cir. 2000). That "a" or "an" can mean "one or more" is best described as a rule, rather than merely as a presumption or even a convention. The exceptions to this rule are extremely limited: a patentee must "evince[ ] a clear intent" to limit "a" or "an" to "one." Id. The subsequent use of definite articles "the" or "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. An exception to the general rule that "a" or "an" 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. See, e.g., Abtox Inc. v. Exitron Corp., 122 F.3d 1019 (Fed. Cir. 1997); Insituform Techs., Inc. v. Cat Contracting, Inc., 99 F.3d 1098 (Fed. Cir. 1996).

Some terms simply can't be contained. 'Comprising' and its variants: 'comprised of,' 'including,' 'having,' 'containing,' and even 'wherein' are broadly interpreted, while 'consists of' is a skinny little brother. CIAS v. Alliance Gaming and Bally Gaming:

In the patent claim context the term "comprising" is well understood to mean "including but not limited to." In Vivid Techs., Inc. v. Am. Sci. & Eng'g, Inc., 200 F.3d 795, 811 (Fed. Cir. 1999) the court explained that patent claims "use the signal 'comprising,' which is generally understood to signify that the claims do not exclude the presence in the accused device or method of factors in addition to those explicitly recited." In Georgia-Pacific Corp. v. United States Gypsum Co., 195 F.3d 1322, 1327-28 (Fed. Cir. 1999) the court explained that "the terms 'comprise' and 'consist' have different meanings; . . . 'comprising' . . . is inclusive or open-ended and does not exclude additional, unrecited elements or method steps . . . . From these definitions it is clear that 'comprise' is broader than 'consist.'" Similarly, our predecessor court explained that this usage of "comprising" also embraces "comprises" and "which comprises." Application of James F. Hunter, 288 F.2d 930 (CCPA 1961) (the term "comprises" does not limit the claim to the steps that are listed).

The contrast, in patent lexicography, is with "consisting of," not with variations of "comprises." It is equally well understood in patent usage that "consisting of" is closed-ended and conveys limitation and exclusion. See Norian Corp. v. Stryker Corp., 363 F.3d 1321, 1331 (Fed. Cir. 2004) ("'consisting of' is a term of patent convention meaning that the claimed invention contains only what is expressly set forth in the claim . . . [however] it does not limit aspects unrelated to the invention"); In re Gray, 53 F.2d 520 (CCPA 1931) (the use of the claim term "consists" is limited to the claim's enumerated alloy metals without other elements, unlike the term "comprising" which permits the inclusion of other metals than those claimed"). Robert A. Faber, Landis on Mechanics of Patent Claim Drafting '2:5, 2-15 (5th ed. 2006) also elaborates that "[o]ther words, less often used, have been given the same meaning in patent claim interpretation as 'comprising': 'including,' 'having,' 'containing,' and even 'wherein.'"

Hoary ordinary words have come in for some rough handling by the courts: 'only if' and 'between' being recent examples. Don't neglect simple terms in claim construction. Regardless of district courts desire to simplify patent cases, prepare for appeal from the get-go by presenting comprehensive claim construction.

Claims with range, literally, can encounter a precision dilemma. The difference between '1' and '1.0' is precision. But claiming a specific numeric range does not necessarily limit claim scope, either towards DOE or obviousness. U.S. Phillips v. Iwasaki Electric:

In Abbott Laboratories, we noted that "the fact that a claim recites numeric ranges does not, by itself, preclude . . . [reliance] on the doctrine of equivalents." 287 F.3d at 1107-08. Indeed, in that case, we allowed consideration of the doctrine of equivalents as to such a range. Id. at 1100 (discussing claim to a material "characterized in that the overall phospholipid content is 68.6-90.7%"); see also Warner-Jenkinson, 520 U.S. at 32-33 (permitting consideration of the doctrine of equivalents with respect to a claim to a pH range "from approximately 6.0 to 9.0").

As we observed in DePuy Spine, "[a] holding that the doctrine of equivalents cannot be applied to an accused device because it 'vitiates' a claim limitation is nothing more than a conclusion that the evidence is such that no reasonable jury could conclude that an element of an accused device is equivalent to an element called for in the claim, or that the theory of equivalence to support the conclusion of infringement otherwise lacks legal sufficiency." 469 F.3d at 1018-19.

Too often, the best day for a patent holder is the day an infringement complaint is filed, the case all downhill from there. That's because due diligence is given lip service by lawyers. Most patent plaintiff loses are attributable to foreseeable events. Due diligence includes holistic claim construction, along with examining the repercussions to infringement and validity, up front.