Federal Circuit: Biosig Instruments, Inc. v. Nautilus, Inc.

Patent-at-issue: 5,337,753 ("HEART RATE MONITOR")
Claims-at-issue: 1 (Device, Independent), 11 (Device, Dependent on 1)
Terms-at-issue: "in spaced relationship"
District Court: S.D.N.Y.


  • S.D.N.Y. - Claim 1 invalid for indefiniteness
  • C.A.F.C. - Reverse indefiniteness and remand for infringement
  • S.C.O.T.U.S. - Vacate reversal and remand


  • C.A.F.C. - Maintain reversal


  • What is the proper standard for indefiniteness?


  • Federal Circuit - "A claim is indefinite only when it is not amenable to construction or insolubly ambiguous." (Overturned by SCOTUS)
  • Supreme Court - "[a claim is indefinite] if its claims, read in the 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." (Current Law)
  • Federal Circuit - "When a word of degree is used, the court must determine whether the patent provides some standard for measuring that degree." pg. 6


The successor to Nautilus II, 134 S. Ct. 2120 (2014), the Federal Circuit applies the new "reasonable certainty" test for indefiniteness for the first time.

In doing so, it discusses the necessity of the "spaced relationship" in the context of extrinsic evidence about the claims. In short, the nature of an electromyogram (EMG) monitor instructs those artisans skilled in creating EMGs about the specific space, dependent on other design variables, between the electrodes. Therefore "a spaced relationship" is meaningful, if not necessarily the best claim language that could have been chosen.


The Supreme Court seems to be trying to insert standards of reasonableness into the patent litigation process, ostensibly to give more discretion to district courts to protect legitimate business and dispense with frivolous trolls. However, I have questions about whether a standard of "reasonable certainty" which implies some amount of factual determination in line with a legal conclusion would really serve to stop excess litigation. Bright-line, rigidly-applied rules don't get appealed, at least not with the frequency that determinations that are more factual in nature do. In our zeal to rein in abusive patent litigation through law and policy, we should be careful to choose solutions that protect the strength of legitimate inventors and their rights-buyers without giving ammunition to those who wish to game the system.

Full Decision:

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