The definiteness requirement originates from 35 U.S.C. § 112 ¶ 2. The statute provides that “[t]he specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.” 35 U.S.C. § 112 ¶ 2. If a claim fails to satisfy the definiteness requirement, it is invalid. Bancorp Servs., L.L.C. v. Hartford Life Ins. Co., 359 F.3d 1367, 1371 (Fed. Cir. 2004). “In ruling on a claim of patent indefiniteness, a court must determine whether those skilled in the art would understand what is claimed when the claim is read in light of the specification.” Id.; Exxon Research and Eng’g Co. v. United States, 265 F.3d 1371, 1375 (Fed. Cir. 2001). “A claim is indefinite if its legal scope is not clear enough that a person of ordinary skill in the art could determine whether a particular composition infringes or not.” Geneva Pharm., Inc. v. GlaxoSmithKline PLC, 349 F.3d 1373, 1384 (Fed. Cir. 2003); accord Exxon Research, 265 F.3d at 1375.

The Exxon Research court explained that a claim will not be invalidated for indefiniteness without a severe defect.

[W]e have not held that a claim is indefinite merely because it poses a difficult issue of claim construction. We engage in claim construction every day, and cases frequently present close questions . . . . We have not insisted that claims be plain on their face in order to avoid condemnation for indefiniteness; rather, what we have asked is that the claims be amenable to construction, however difficult that task may be. If a claim is insolubly ambiguous, and no narrowing construction can properly be adopted, we have held the claim indefinite. If the meaning of the claim is discernible, even though the task may be formidable and the conclusion may be one over which reasonable persons will disagree, we have held the claim sufficiently clear to avoid invalidity on indefiniteness grounds.

65 F.3d at 1375 (citing Modine Mfg. Co. v. United States Int'l Trade Comm'n, 75 F.3d 1545, 1557 (Fed. Cir. 1996) (emphasis added) (rejecting indefiniteness argument after claim construction; and stating that “when claims are amenable to more than one construction, they should when reasonably possible be interpreted to preserve their validity.”)). We declared in Exxon Research that “[b]y finding claims indefinite only if reasonable efforts at claim construction prove futile, we accord respect to the statutory presumption of patent validity, and we protect the inventive contribution of patentees, even when the drafting of their patents has been less than ideal.” Id. (internal citations omitted).

The technology involved in the invention of the ‘862 patent is not complex; it is readily understood by both the expert and the layperson. Moreover, as Fisher-Price notes, the words used in the limitation are simple, with well-known ordinary meanings. Under these circumstances, we think the limitation “upper seating surface” can be construed without great difficulty, even if, as Graco points out, it is not mentioned in the specification.

There was an error in Figure 7 that led the district court to invalidate the claim. But, as the CAFC put it...

The clerical error in Figure 7 is not fatal because the claim language is unambiguous. It clearly defines the “reconfigurable swing area” as the area between the swing arm and the frame support post....

There was an inconsistency in the specification with regard to coupling a shield to the seat. But, clear claim language overrides such specification conflict, ruled the CAFC.

Even if it could be said that a conflict exists within the specification, it is resolved by the unambiguous claim language, which teaches “a shield coupled to said seat.” Given the clarity of the claim language, we are confident that insofar as the first part of the shield limitation is concerned, reasonable efforts at claim construction would not prove futile. See Exxon Research, 265 F.3d at 1375.

There was contention that the phrase "said seating area" in an asserted claim lacked antecedent basis. Fisher-Price contended "that “upper seating surface” is the antecedent basis for “said seating area.”"

Graco responds that allowing “upper seating surface” to serve as the antecedent basis for “said seating area” essentially equates the terms, which Graco argues is impermissible. See Ethicon Endo-Surgery Inc. v. United States Surgical Corp., 93 F.3d 1572, 1579 (Fed. Cir. 1996) (stating that if the two claim terms at issue “described a single element, one would expect the claim to consistently refer to this element as either [one or the other of the two terms], but not both, especially not within the same clause”).

A claim is not invalid for indefiniteness if its antecedent basis is present by implication. Cross Med. Prods., Inc. v. Medtronic Sofamor Danek, Inc., No. 05-1043, 2005 WL 2403777, at *23 (Fed. Cir. 2005) (citing Slimfold Mfg. Co. v. Kinkead Indus., Inc., 810 F.2d 1113, 1116 (Fed. Cir. 1987)). It is our conclusion that, in this case, “upper seating surface” is by implication the antecedent basis for “seating area.” On that basis, we hold that the second half of the shield limitation of claim 6 is not indefinite.

For the foregoing reasons, the decision of the district court holding the asserted claims of the ‘862 patent indefinite and dismissing Fisher-Price’s suit is reversed. The case is remanded to the district court for it to construe the asserted claims and to thereafter adjudicate Fisher-Prices’ claim of infringement.