[JURIST] The US Supreme Court [official website] ruled [opinion, PDF] unanimously Monday in Nautilus, Inc. v. Biosig Instruments, Inc. [SCOTUSblog backgrounder], a long-running patent infringement case. Biosig sued Nautilus [corporate websites] in 2004, alleging that Nautilus infringed its patent for a heart-rate monitor. A district court found Biosig’s patent invalid because of “indefiniteness.” However, the US Court of Appeals for the Federal Circuit reversed the lower court and found that the patent was clear and valid, as long as the ambiguity is not insoluble. In an opinion by Justice Ruth Bader Ginsburg, the Supreme Court vacated the Federal Circuit’s decision:

The Patent Act requires that a patent specification “conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as [the] invention.” … This case, involving a heart-rate monitor used with exercise equipment, concerns the proper reading of the statute’s clarity and precision demand. According to the Federal Circuit, a patent claim passes the §112, ¶2 threshold so long as the claim is “amenable to construction,” and the claim, as construed, is not “insolubly ambiguous.” … We conclude that the Federal Circuit’s formulation, which tolerates some ambiguous claims but not others, does not satisfy the statute’s definiteness requirement. In place of the “insolubly ambiguous” standard, we hold 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.

The court did not determine whether Nautilus had infringed Biosig’s patent, remanding the case for further proceedings in the lower court.

The court heard arguments in the case in April after granting certiorari [JURIST reports] in January. JURIST Guest Columnist Charles Duan of the Patent Reform Project at Public Knowledge [advocacy website] discussed problems in patent law and the Nautilus in a recent op-ed [text].