US Supreme Court Instructs CAFC to Tighten Up its Indefiniteness Analysis

Ken Salen | June 4, 2014

Nautilus, Inc. v Biosig Instruments, Ins.

June 2, 2014

Associate Justice Ginsberg delivered the opinion for a unanimous United States Supreme Court


The Court of Appeals for the Federal Circuit (CAFC) previously was said to go to great lengths to construe claim limitations and rarely find that a claim is invalid as indefinite. Today, the CAFC was warned by the United States Supreme Court (SCOTUS) to reign in its liberalness with respect to not finding indefiniteness.

The issues at hand in the case were (1) whether the CAFC’s acceptance of ambiguous patent claims with multiple reasonable interpretations – so long as the ambiguity is not “insoluble” by a court – defeats the statutory requirement of particular and distinct patent claiming; and (2) whether the presumption of validity dilutes the requirement of particular and distinct patent claiming.

Case remanded to CAFC to reconsider, under a newly articulated standard, whether the relevant claims in the ’753 patent are suffi­ciently definite.


The Biosig ’753 patent involves a heart-rate monitor used with exer­cise equipment. Prior heart-rate monitors were often inaccurate in measuring the electrical signals accompanying each heartbeat (electrocardiograph or ECG signals) because of the presence of other electrical signals (electromyogram or EMG signals), generated by the user’s skeletal muscles, that can impede ECG signal detection. The invention improves on prior art by detecting and processing ECG signals in a way that filters out the EMG inter­ference.

Fig 7 '753 patent









Claim 1 of the Biosig ’753 patent is directed to a heart rate monitor for use by a user in asso­ciation with exercise apparatus and/or exercise procedures. The claim includes, among other elements, a cylindrical bar fitted with a display device; electronic circuitry including a difference am­plifier; and, on each half of the cylindrical bar, a “live” electrode and a “common” electrode “mounted…in spaced relationship with each other.”

The District Court, after conducting a Markman hearing to determine the proper construction of the patent’s claims, granted Nautilus’ motion for summary judgment on the ground that the claim term “in spaced relationship with each other” failed the 35 U.S.C. §112, second paragraph definiteness requirement because “spaced” was not sufficiently defined.

The CAFC, as reported by WHDA on May 9, 2013, reversed the District Court and re­manded, concluding that a patent claim passes the §112, second paragraph thresh­old if the claim is “amenable to construction,” and the claim, as construed, is not “insolubly ambiguous.” Under that stiff standard for finding indefiniteness, the court determined, the ’753 patent survived indefiniteness review.

At that time, the CAFC held, with respect to indefiniteness analysis:

A patent is invalid for indefiniteness if its claims, read in light of the patent’s specification and prosecution history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.

Claims are to be read in light of the patent’s specification and prosecution histo­ry.

Definiteness is to be measured as of the time of the pa­tent application.

Definiteness must take into account the inherent limitations of language.… On the one hand, some modicum of uncertainty is the “price of ensuring the appropriate in­centives for innovation….” On the other hand, a patent must be precise enough to afford clear notice of what is claimed, thereby “apprising the public of what is still open to them” in a manner that avoids a “zone of uncertainty which enterprise and experimentation may enter only at the risk of infringement claims.

Opinions of the CAFC previously stated that “the certainty which the law requires in patents is not greater than is reasonable, having regard to their subject-matter.”

On the question of claim construction, the CAFC determined from the specification certain simple limits on the meaning of “spaced relationship,” creating an upper limit and a lower limit.

[The] electrode cannot be greater than the width of a user’s hands because claim 1 requires the live and common electrodes to independently detect electrical signals at two distinct points of a hand. On the other hand, it is not feasible that the distance between the live and common electrodes be infinitesimally small, effectively merging the live and common electrodes into a single electrode with one detection point.

Nautilus brought the present appeal to the Supreme Court, wherein the SCOTUS unanimously held that the CAFC previous standard had set the bar too low in allowing patents to be written vaguely.

In the present case, the requirement that the ’753 patent’s claims were “amenable to construction” or “insolubly ambiguous” mimicking the standards adopted by the CAFC’s recent decisions concerning §112 second paragraph rejections, fails to satisfy the statute’s requirements and can leave courts and the patent bar “at sea without a reliable compass.”

The SCOTUS held that to “tolerate imprecision just short of that rendering a claim “insolubly ambigu­ous” would diminish the definiteness requirement’s public-notice function and foster the innovation-discouraging “zone of uncertainty.”

The decision also recognizes that the old rule offers an incentive for patentees to intentionally “inject ambiguity into their claims.” The new standard is intended to help eliminate that standard.

It cannot be sufficient that a court can ascribe some meaning to a patent’s claims. The definiteness inquiry is based on the understanding of one skilled in the art at the time of the patent application, rather than that of a court viewing matters post hoc. The SCOTUS emphasized that, “To tolerate imprecision just short of that rendering a claim “insolubly ambiguous” would diminish the definiteness requirement’s public-notice function and foster the innovation-discouraging “zone of uncertainty,” against which this Court has warned.”

The new standard articulated by the SCOTUS is:

“[T]o require that a patent’s claims, viewed in light of the specification and prosecution history, inform those skilled in the art about the scope of the invention with reasonable certainty. The definiteness requirement, so understood, mandates clarity, while recognizing that absolute precision is unattainable. The standard we adopt accords with opinions of this Court stating that “the certainty which the law requires in patents is not greater than is reasonable, having regard to their subject-matter.” See also United Carbon, 317 U.S. at 236 (“claims must be reasonably clear-cut”); Markman, 517 U.S. at 389 (claim construction calls for “the necessarily sophisticated analysis of the whole document,” and may turn on evaluations of expert testimony).”

The court gave little additional guidance on the definition of “reasonable certainty,” but did note that the “Federal Circuit’s fuller explications of the term ‘insolubly ambiguous’ … may come closer to tracking the statutory prescription.” The case is now remanded back to the CAFC for a decision under the correct standard.

It now falls to the CAFC to provide further guidance on the correct application of the newly articulated “reasonable certainty” standard. More specifically, the CAFC must determine whether in this case the disputed claim term “spaced relationship” (relating to electrodes on a heart monitor, e.g., built into an exercise machine), when read in light of the specification and the prosecution history, gives those with skill in the relevant art the kind of “reasonable certainty” about the scope of the invention that is required.

Takeaways and Concerns

  • To the extent the USPTO increases scrutiny of indefiniteness in view of this case, it may increase the need to rely on declarations from one of ordinary skill in the art during prosecution, or may involve greater consideration of descriptions of terms in the specification, such as tying ranges to some functional objective, or providing more examples. Careful attention from firms such as WHDA can particularly help foreign applicants avoid unintentional invalidity.
  • The Court’s reference to considering ambiguity “at the time the patent was filed” and considering the prosecution history in determining ambiguity should not be interpreted to raise questions as to when ambiguity exists (i.e., during an amendment, at patent issuance, or at the foreign priority date). The “date of the invention” in §112 (pre-AIA) is the US filing date (or the PCT filing date if a national stage of the PCT application). Applicant’s prosecution history plays into the understanding of one skilled in the art “at the time the patent was filed.” There is no separate inquiry as to the skilled artisan’s understanding at different times such as at patent issuance, or on the date of various applicant responses in the prosecution history.
  • This case, combined with the concurrent Limelight decision, will provide handy tools for courts to rule against alleged “patent trolls” by finding claims invalid or not infringed.

Subscribe | 登録



词典 / 辞書 / 사전
  • dictionary
  • dictionary
  • 英語から日本語

Double click on any word on the page or type a word:

Powered by