Nautilus, Inc v. Biosig Instruments Inc.

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LII note: The U.S. Supreme Court has now decided Nautilus, Inc v. Biosig Instruments Inc..


How specific and clear must a patent be to balance the Patent Act’s purposes of (1) protecting inventors and the public and (2) avoiding excess costs and litigation?

Oral argument: 
April 28, 2014

Since the 1990s, Nautilus and Biosig Instruments have had a series of patent disputes. Their current dispute involves a new model of heart rate monitors mounted onto exercise equipment. Nautilus contends that Biosig’s patent is indefinite as a matter of law and therefore invalid. Further, Nautilus argues that patents must provide sufficiently clear notice to protect the public, promote innovation, and reduce costs to the judicial system. Biosig counters that its patent is valid because it is sufficiently clear and specific to meet the standards of definiteness set by precedent. Biosig further argues that a patent should be broad enough to protect innovators and their still-developing products. The Federal Circuit held that Biosig’s patent was valid because it was not “insolubly ambiguous.” The Supreme Court’s decision will impact the requirements inventors and drafters must meet to patent new technologies.

Questions as Framed for the Court by the Parties 

  1. Does the Federal Circuit’s acceptance of ambiguous patent claims with multiple reasonable interpretations—so long as the ambiguity is not “insoluble” by a court—defeat the statutory requirement of particular and distinct patent claiming?
  2. Does the presumption of validity dilute the requirement of particular and distinct patent claiming?
  3. Whether a patent claim is invalid for indefiniteness where the traditional tools of claim construction establish its meaning, simply because lawyers may devise other interpretations, years after issuance, that are not “outlandish” or “implausible”?
  4. Whether an accused infringer challenging a patent claim as indefinite may overcome the statutory presumption of validity, 35 U.S.C § 282(a), without introducing any evidence that a person skilled in the art would have been unable to understand the claim’s meaning?



Biosig Instruments, Inc. and Nautilus, Inc. have had an ongoing dispute since the late 1990s, when Nautilus’ predecessor, StairMaster Company, began selling exercise equipment that Biosig claims infringes its patented technology. Biosig holds U.S. Patent No. 5,337,753 (“the ’753 patent”). The ‘753 patent protects a heart rate monitor mounted onto exercise equipment. The patent purportedly improves upon previous models by more accurately measuring heart rate.

In 2004, Biosig brought a patent infringement suit against Nautilus claiming that Nautilus had infringed claims 1 and 11 of the ’753 patent. During the litigation, Nautilus twice asked the United States Patent and Trademark Office (“PTO”) to reexamine the ’753 patent. These requests were based on U.S. Patent No. 4,444,200 (“Fujisaki”). After the first reexamination, the PTO rejected claim 1 as anticipated by Fujisaki and claim 11 as obvious over Fujisaki given other prior art references.

After the second reexamination of the ’753 patent, the PTO ultimately confirmed its patentability. Thereafter, Biosig reinstituted its patent infringement action against Nautilus. In November 2011, Nautilus moved for summary judgment, arguing non-infringement and that Biosig’s patent was invalid for indefiniteness.

The U.S. District Court for the Southern District of New York denied Nautilus’ motion for summary judgment on non-infringement on the grounds that the parties had not completed enough discovery to warrant dismissal. However, the district court granted Nautilus’ motion to dismiss on the invalidity claim, holding that the ’753 patent’s “spaced relationship” term from claim 1 was indefinite as a matter of law.

Nautilus filed a third request for reexamination of the ’753 patent with the PTO after the parties submitted their summary judgment briefs but before the hearing. The PTO denied this request, finding that there were no new questions of patentability raised in the request. In response, Biosig asked the district court to reconsider its decision on the motion for summary judgment in light of the PTO’s decision. The district court denied the request.

On appeal from the district court’s opinion, the Federal Circuit reversed the district court’s motion to dismiss based on invalidity, stating that the patent was not “insolubly ambiguous.” The Supreme Court granted certiorari.



Nautilus argues that the Patent Act serves two primary purposes: (1) to protect the public by providing clear notice of a patent’s scope and to promote innovation, and (2) to ensure that the costs of proving patentability remain with the party seeking the patent. Biosig argues that a certain degree of indefiniteness is necessary to reward inventors for their efforts and to protect them from litigation. The Supreme Court’s resolution of this case may impact the standard for patent claim indefiniteness and the level of specificity a patentee must satisfy before receiving a patent.

Protecting the public and promoting innovation

Nautilus argues that the primary purpose of the Patent Act is to provide clear notice of a patent’s scope. Nautilus and supporting amici explain that clear notice prevents patentees from making vague and overly broad patent requests. Such patents, they argue, create a “zone of uncertainty” that discourages innovation by other entities. Nautilus argues that if inventors are allowed to make ambiguous patent claims, it will be harder for other innovators to know what is and is not already patented. Nautilus argues that, because potential innovators fear the costs of uncertainty and litigation, this will lead to a chilling effect on innovation altogether. According to Nautilus and its supporters, this situation would entirely undermine the purpose of the Patent Act to promote innovation.

Biosig responds that although one purpose of the Patent Act is to give the public notice of where innovation is legally permitted, another purpose is to reward the inventor for his work. As such, the Supreme Court’s precedent recognizes a strong presumption in favor of protecting the validity of the patent. Furthermore, Biosig notes that in its decisions, the Court has held that the reasonableness standard in the Patent Act is based on what a person skilled in the relevant art would understand. Additionally, Biosig argues that indefiniteness is a necessary feature in patent applications to allow industry to work on technologies with functions that are still developing.

Burden and Cost shifting

Nautilus notes that another purpose of the Patent Act is to enable courts and the PTO to determine whether an innovation is patentable. Nautilus argues that because there are millions of valid patents at any given time, it can be very cumbersome and costly for courts to determine whether an invention is novel and patentable. As such, Nautilus and its supporters argue that by requiring patent seekers to clearly distinguish their innovations and bear the burden of doing the research on patentability upfront, courts and the PTO can save valuable resources. For Nautilus, this is particularly reasonable given that the inventor, who knows his invention best, is in the best position to prevent ambiguities in the patent claim.

Biosig argues that if the Court rules in favor of Nautilus, infringers will be incentivized to frustrate courts’ role in construing patent claims, which will only increase litigation. Specifically, Biosig argues that if the Court adopts Nautilus’ rule for patent specificity, litigation will increase Biosig contends that a party sued for infringement would waste court resources by challenging the precision of every aspect of the patent. The result, Biosig claims, would be “more prevalent and more labored” patent litigation.



The issue before the Court is the validity of Biosig’s patent. Nautilus argues that the Biosig patent is invalid for ambiguity. Biosig maintains, however, that a patent claim need not be perfect; it merely needs to be reasonably clear to inform one skilled in the relevant art of its meaning. According to Biosig, the patent in question meets that standard.


Nautilus’s argument begins by looking at the text of the Patent Act. Natulus explains that, under the Act, applicants are required to submit a “specification” which defines the scope of the applicant’s purported invention. The first part of the specification is a written description of the invention. The second part, which lies at the heart of this case, requires an applicant to “particularly point[] out and distinctly claim[]” the subject matter of the invention. According to Nautilus, the Act’s requirement that a patent claim be “particular” and “distinct” means that any ambiguous claims—claims which are susceptible to more than one reasonable interpretation—are expressly void under the law. Nautilus contends that whether a patent claim is ambiguous ought to be determined by the objective standard of one “skilled in the relevant art.” Thus, according to Nautilus, if someone skilled in the art covered by the patent cannot clearly discern from the application what single invention the patent actually covers, then the claim is ambiguous and, in turn, void under the Patent Act.

According to Biosig, however, in order to meet the “definiteness” requirement of the Patent Act, a patent claim only needs to be able to convey to one skilled in the relevant art the “metes and bounds” of the patent; it does not need to exactly describe the precise invention in question. In support of its contention, Biosig argues that language is inherently limited and cannot be expected to perfectly describe every new invention, and that the very nature of certain inventions may necessitate using language that on its face appears ambiguous, but which in context is reasonably clear to one skilled in the relevant art.

Biosig maintains, moreover, that the Court has had to develop a series of rules that are used in construing patents when disputes arise since it is not always possible to set out in the patent claim every imaginable way an invention may be enabled. Biosig points as an example to the so-called “doctrine of equivalents,” under which patent infringement may be found even if the infringing product does not violate the literal terms of the patent claim, as long as the infringing element is somehow “equivalent” in manner. Hence, Biosig argues, uncertainty in a patent claim does not render that claim invalid per se; rather, courts will endeavor to interpret the patent in the most coherent manner possible.

Nautilus relies on what it classifies as a long history in the Supreme Court of interpreting the Patent Act to protect the public by requiring that patent claims clearly delimit the boundaries of their inventions. According to Nautilus, if a patent claim is so ambiguous that it could plausibly cover a range of inventions, then other inventors will be discouraged from creating new inventions that might infringe the ambiguous patent. In turn, the cost of liability for patent infringement, plus the cost of defending oneself in an infringement suit is too high, according to Nautilus, for the public to risk possibly infringing a patent. Accordingly, Nautilus argues that Congress purposely required applicants to clearly define the boundaries of their patents so that others could confidently work around them. To serve the public interest, then, Nautilus asserts that patent claims must be clear and precise so that innovation and progress are not unnecessarily stifled. Moreover, Nautilus argues that clearly defined patent claims assist courts in interpreting patents.

According to Nautilus, the lower court’s opinion in this case directly undermines Congress’s purpose in enacting the Patent Act. The Federal Circuit held that a patent claim is invalid only when it is not “amenable to construction” or when, after an attempt at construing the claim, it is found to be “insolubly ambiguous,” meaning that attempts at defining the patent claim do not provide any meaningful understanding of its bounds. Nautilus argues that this standard deprives the public of the benefit of a clearly defined patent claim at the time it is written, and instead allows courts to determine the boundaries of a patent perhaps years after its issuance. Nautilus contends that such uncertainty is directly contrary to the Patent Act’s purpose and Supreme Court precedent.

Biosig counters, however, that Nautilus’ interpretation of the standard for specifying claims is entirely unworkable. Biosig argues that under Nautilus’ proposed test, a claim is per se invalid if it is susceptible to more than one reasonable interpretation. Biosig contends that this stark rule flies in the face of historical practice, and that courts have routinely interpreted patents despite reasonable disputes about their meaning. Indeed, Biosig argues, the Court held in Markman v. Westview Instrument, Inc. that claim construction is for judges, not juries, because of the inherent difficulties involved in that process. Markman, according to Biosig,sets out a process for ascertaining the meaning of patent claims and implicitly recognizes that a claim is not invalid simply for being ambiguous. Rather, Biosig argues, claims with competing interpretations are construed by judges. If Nautilus’s interpretation of the Patent Act were to prevail, Biosig argues, the delicate balance Congress struck between rewarding innovation and encouraging new inventions would be destroyed.


Nautilus maintains that whether Biosig’s patent claim was sufficiently “particular” and “distinct” is a question of law that the Court can and should decide. Nautilus points out that the majority and concurring opinions issued by the Federal Circuit state that the patent in question is susceptible to more than one reasonable interpretation. In Nautilus’s view, this shows that the patent at issue does not meet the Patent Act’s “particular” and “distinct” requirements.

Biosig counters that if a patent claim can be construed in two possible ways, then a court should adopt whatever construction will uphold the patent rather than invalidate it. According to Biosig, this is consistent with the principle that the law should seek to avoid forfeitures; that is, rules that cause a party to lose all of its rights are disfavored. Thus, the fact that a patent may be susceptible to more than one reasonable interpretation does not mean that it is void. Rather, courts will attempt to interpret the patent in a manner that seeks to preserve the patentee’s legal rights. Under that rule, Biosig maintains that the patent in this case should be upheld. Moreover, Biosig points to the presumption of validity afforded to patents—it is the responsibility of the party challenging the patent to demonstrate that its invalidity. According to Biosig, Nautilus has failed to overcome its burden in proving that the patent here is invalid.



In this case, the Court will consider whether a patent held by Biosig is valid under the Patent Act. Nautilus maintains that the patent is invalid because it is ambiguous and thus violates the Patent Act’s requirement that patent claims be “distinct” and “particular.” Biosig contends that a patent claim only needs to be reasonably clear to inform one skilled in the relevant art of its meaning, and that the patent in question clearly meets this standard. In deciding this case the Court will construe § 112 of the Patent Act and determine what is required in the specification of a patent claim. The Court’s decision will impact how patent claims are drafted, how they are reviewed by the Patent and Trademark Office, and how courts will construe them in litigation.


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