According to the standard for indefiniteness, whether a claim is invalid for indefiniteness would have to be determined at the time the claim is construed, not after. This is because the standard is whether the claim can be construed at all. See, e.g., Praxair, Inc. v. ATMI, Inc., 543 F.3d 1306, 1319 (Fed. Cir. 2008) (“A claim will be found indefinite only if it is insolubly ambiguous, and no narrowing construction can properly be adopted…. On the other hand, 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.”) (internal quotation marks and citations omitted); see also id. (“Indefiniteness is a matter of claim construction ….”).
Notwithstanding this standard, a defendant will often adopt the strategy of seeking a preferred construction and arguing that if the court adopts the patentee’s proposed construction the claim would be indefinite. And sometimes defendants will, after the court has construed the claims, argue that the adopted construction is indefinite. While the case law is not clear regarding the timing for deciding the issue of indefiniteness, the standard for indefiniteness should force defendants to decide early on, i.e., when proposing claim constructions, whether to pursue a defense of indefiniteness. A defendant should not be able to propose a definition for a term and later argue that the very same term is insolubly ambiguous. If a term can’t be construed, there should be no proposed construction for it. Therefore, a defendant should state its belief that a particular claim is indefinite when proposing constructions, and the court should decide this issue in the Markman ruling.