In Biosig Instruments, Inc. v. Nautilus, Inc., No. 12-1289 (Fed. Cir. Apr. 27, 2015), the Federal Circuit, on remand from the Supreme Court, maintained its reversal of the district court’s determination that Biosig Instruments, Inc.‘s (“Biosig”) patent claims are indefinite, and remanded the case to the district court for further proceedings.

Biosig is the assignee of U.S. Patent No. 5,337,753 (“the ’753 patent”), directed to a heart rate monitor associated with an exercise apparatus and/or exercise procedures. Biosig sued Nautilus, Inc. (“Nautilus”) in district court, alleging infringement of the ‘753 patent. Following claim construction, Nautilus moved for SJ, seeking, in relevant portion, to have the ‘753 patent held invalid for indefiniteness. The district court granted SJ, holding that the term “spaced relationship,” referring to the spacing between two electrodes, is indefinite. Biosig appealed. The Federal Circuit found the claims not invalid for indefiniteness under the “not amenable to construction or insolubly ambiguous” standard. Slip op. at 4 (citing Nautilus, Inc. v. Biosig Instruments, Inc. (“Nautilus I”), 715 F.3d 891, 898 (Fed. Cir. 2013)), and reversed and remanded the case for further proceedings. Nautilus petitioned for certiorari.

On appeal, the Supreme Court rejected the Federal Circuit’s “not amenable to construction or insolubly ambiguous” standard. Clarifying the proper standard to be applied for indefiniteness, the Supreme Court held that “a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecution history, fail to inform, with reasonable certainty those skilled in the art about the scope of the invention.” Id. (citing Nautilus, Inc. v. Biosig Instruments, Inc. (“Nautilus II”), 134 S. Ct. 2120, 2124 (2014)). The Supreme Court vacated and remanded the Federal Circuit’s decision without opinion on the validity of the asserted patent but with instruction to decide the case under its prescribed standard.

Applying the Supreme Court’s articulated standard on remand, the Federal Circuit maintained its reversal of the district court’s determination that the claims were indefinite. As an initial matter, the Federal Circuit clarified that in Nautilus II, the Supreme Court “modified the standard by which lower courts examine allegedly ambiguous claims; we may now steer by the bright star of ‘reasonable certainty,’ rather than the unreliable compass of ‘insoluble ambiguity.‘” Id. at 9. The Federal Circuit emphasized that “reasonable certainty” is a ”[f]amiliar [s]tandard” to the courts. Id. at 8. Citing several Supreme Court decisions, the Federal Circuit stated that “reasonable certainty” is the core of much of the common law and has been defined by the Supreme Court in many contexts. The Federal Circuit also indicated that a number of its own cases had already applied a “reasonable certainty” standard in various contexts other than indefiniteness prior to Nautilus II, and that three of its own cases have applied the “reasonable certainty” standard since Nautilus II.

Against this background and the Supreme Court’s articulated standard in Nautilus II, the Federal Circuit revisited the intrinsic evidence and its prior analysis in Nautilus I and found that the asserted claims inform a skilled artisan with reasonable certainty. Specifically, the Court relied on its previous findings in Nautilus I that the claim language, specification, and figures illustrating the “spaced relationship” provided sufficient clarity to one skilled in the art as to the parameters of the claim term. The Court noted that a skilled artisan would understand that the claims require that the spaced relationship be “neither infinitesimally small nor greater than the width of a user’s hands” because (1) the asserted claims require detection of electrical signals at two distinct points of a user’s hand, and (2) it is not feasible for the electrodes to be infinitesimally small such that electrodes are effectively merged into one detection point. Id. at 15-16.

The Court also relied on the prosecution history of the asserted claims to further support its conclusion that the disputed term is not indefinite. Specifically, the Court referred to its consideration in Nautilus I of the functionality of the claimed heart rate monitor in which electrical signals are removed based in part on the “spaced relationship” of the electrodes, which provided the basis for patentability of the claims. In the Court’s view, the recited function in the asserted claim is “highly relevant” to ascertaining the boundaries of the disputed term and further provides a method that skilled artisans could apply to determine the “spaced relationship” of the electrodes. Id. at 17. The Court also highlighted the inventor’s declaration submitted during prosecution and his testimony in Nautilus I, which the Court stated further illustrates that when configuring the claimed heart rate monitor, skilled artisans can determine the “spaced relationship” between the two electrodes by calculating the point in which signals are removed.

Accordingly, the Federal Circuit concluded that ”[t]he term ‘spaced relationship’ does not run afoul of the innovation-discouraging ‘zone of uncertainty’ against which [the Supreme Court] has warned, and to the contrary, informs a skilled artisan with reasonable certainty of the scope of the claim.” Id. at 18 (second alteration in original) (quoting Interval Licensing LLC v. AOL, Inc., 766 F.3d 1364, 1374 (Fed. Cir. 2014)) (internal quotation marks omitted). Thus, the Court maintained its reversal of the district court’s determination that the asserted claim is invalid for indefiniteness and remanded the case for further proceedings.