By Jessica F. Winchester and Jameson Q. Ma, Bookoff McAndrews PLLC

Law360, New York (March 25, 2014, 1:36 PM ET) — The U.S. Supreme Court’s upcoming consideration of the insolubly ambiguous indefiniteness standard is further evidence of a movement in U.S. patent law toward more definite patent claims. A new indefiniteness standard, or a revised interpretation of the indefiniteness standard, may have wide-reaching effects on patent enforcement. Patents issued under the old indefiniteness standard may be more susceptible to invalidity assertions for lack of clarity in patent litigations and in post-grant review proceedings before the U.S. Patent and Trademark Office. Patent practitioners should recognize this movement toward more clarity when drafting and prosecuting patent applications.

Biosig v. Nautilus

The question before the Supreme Court arose from Biosig Instruments Inc. v. Nautilus Inc.,[1] in which the Federal Circuit held that the claim term “spaced relationship” was not insolubly ambiguous. Biosig is the assignee of U.S. Patent No. 5,337,753 which is directed to heart rate monitors installed on exercise equipment (e.g., stationary bikes). Biosig accused Nautilus of infringing certain claims of the ’753 patent that require “[a] heart rate monitor” having “live electrode[s]” and “common electrode[s]” where certain live electrodes and common electrodes are in a “spaced relationship” with each other.

What Is a “Spaced Relationship”?

The district court found the claims of the ’753 patent to be invalid because the phrase “spaced relationship” was ambiguous. The Federal Circuit disagreed, citing well-established precedent that a claim is indefinite only when it is (1) not amendable to construction or (2) insolubly ambiguous.[2]

While the ’753 patent did not define the phrase “spaced relationship” with actual parameters, e.g., that the electrodes were separated by a particular distance, the Federal Circuit found the claim to be sufficiently clear. For example, because the independent claim required the electrodes to independently detect electrical signals at two points of a hand, the court reasoned that the spaced relationship could not be greater than the width of a user’s hand.

Further, the lower limit of a “spaced relationship” could not be so infinitesimally small as to effectively merge the two electrodes. The Federal Circuit found that these inherent parameters disclosed by the ’753 patent set forth sufficient metes and bounds of the “spaced relationship,” and that the claim was definite.[3]


The Supreme Court granted Nautilus’ petition for certiorari on Jan. 10, 2014, and oral arguments are set for April 28, 2014, in what will be a closely followed case in the patent community. The granting of certiorari evidences a desire to revisit the indefiniteness standard.

Is the Federal Circuit Circumventing Public Notice?

The Supreme Court has long held that “[t]he object of the patent law in requiring the patentee to [distinctly claim his invention] is not only to secure to him all to which he is entitled, but to apprise the public of what is still open to them.”[4]

This is the core of the patent system’s public-notice function, and is codified by pre-AIA 35 U.S.C. 112, Second Paragraph (post-AIA 35 U.S.C. 112(b)). Nautilus argues that the Federal Circuit’s indefiniteness standard does not serve this public-notice function, alleging that “the Federal Circuit has shifted the public-notice function from the issued patent claim to a court’s claim construction announced years later or, even, after the patent has expired.”[5]

Nonpracticing Entities

While the legal basis of Nautilus is related to indefiniteness and patents’ public-notice function, there are other, perhaps more significant policy implications that accompany the Supreme Court’s pending decision. The effects of NPEs, or patent assertion entities, on the U.S. economy are in the national spotlight, and are the subject of recent legislative and executive action.

NPEs are often accused of asserting ambiguous patent claims to help extract settlements from alleged infringers.[6] Therefore, with Nautilus, the Supreme Court may weigh in on the NPE debate by providing a new standard for indefiniteness. However, any change to the indefiniteness standard to address NPEs will have the same effect on other patentees, e.g., non-NPEs that use patents to protect their product development efforts.

Additional Evidence of a Movement

Further support for the movement within the patent community toward more patent claim clarity is evidenced by the USPTO’s Supplementary Examination Guidelines[7] which discuss the treatment of “terms of degree” and “subjective terms” during examination. These guidelines suggest that examiners should determine whether the specification provides some standard for measuring the degree or scope of these claim terms and if not, whether a one could ascertain the scope of such terms based on intrinsic evidence. These instructions to the examining corps indicate a desire by at least the USPTO for more precision in patent claims. In a pledge to protect innovators, the White House showed support for the USPTO’s efforts to promote patent clarity.[8]

Staying Ahead of the Curve

In view of the uncertainty surrounding the indefiniteness standard, patent prosecutors should consider how best to draft their applications to survive any potential change in the clarity landscape, while avoiding unnecessarily narrow claims.

Specification Support

Clarity issues are best solved by reference to the specification. Whether the clarity issue relates to a pending or patented claim, clear and detailed support for the claim language in the specification can help overcome any alleged indefiniteness. For example, allegedly indefinite language can be clarified by amendment during prosecution if support exists in the specification, or the definiteness of a patented claim can be argued with reference to the intrinsic evidence of the specification. Thus, it may be more important than ever to draft patent specifications with as much detail as possible, especially as it relates to those features that are recited in the claims.

This use of specification support can be particularly important in providing parameters for so called “relative terms” or “terms of degree” that are subject to indefiniteness challenges. For example, terms such as “about” and “substantially” are more susceptible to an indefiniteness attack at the USPTO or during litigation if the specification lacks of some defined value or parameter in the specification for the term.

Thus, application drafters may consider clearly defining these relative terms in the specification to avoid potential indefiniteness validity challenges (e.g., defining that the space between the common and live electrodes is between 0.01 mm and 15 mm). It is important, however, to note the distinction between definiteness and breadth. Providing supporting clarity in the specification for a claimed feature does not require narrowness in scope. Thus, providing broad but clear definitions in the specification may not only help avoid indefiniteness challenges at the USPTO and during enforcement, but may help provide broad claim constructions.

One approach for practitioners may be to draft patent claims at different points along the definiteness spectrum as a failsafe in case an indefiniteness issue is raised. For example, practitioners may wish to pursue reasonably precise claims and very precise claims so as to protect the patent from an indefiniteness attack. Such an approach may ensure that some commercially significant claims remain standing after an indefiniteness attack.


The Supreme Court’s review of Nautilus evidences a movement toward more definite patent claims, and may have wide reaching-effects on all segments of the patent community. Patent practitioners and patentees should execute forward-thinking prosecution strategies to hedge against any tightening of the indefiniteness standard. That much is definite.

Jessica Winchester and Jameson Ma are associates for Bookoff McAndrews PLLC in Washington, D.C.

The opinions expressed are those of the author(s) and do not necessarily reflect the views of the firm, its clients, or Portfolio Media Inc., or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.

[1] 715 F.3d 891 (Fed. Cir. 2013)

[2] Id. at 898.

[3] Id. at 899.

[4] McClain v. Ortmayer, 141 U.S. 419, 424 (1891)

[5] Petition for a Writ of Certiorari at p. 14.

[6] See Brief of, Inc. et al. as Amici Curiae in Support of Petition for Writ of Certiorari at p. 6-7.

[7] Federal Register, Vol. 76, No. 27, at 7165, Feb. 9, 2011.


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