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Nautilus v. Biosig Instruments

U.S. Supreme Court Sets Higher Bar for Allowing Patents



The Court echoed many arguments in AARP’s friend-of-the-court brief in demanding more clarity in patents which will ultimately increase competition and benefit consumers.


Nautilus v. Biosig concerned a dispute regarding the validity of a heart rate monitor patent on exercise machines and the “insolubly ambiguous” test created by the federal appeals court charged with hearing all patent appeals.  The test allowed inventors with vague patents to exclude competitors in a variety of fields including healthcare.

In this case, Biosig was the owner of a patent which purported to improve upon a prior heart rate monitor patent. Biosig’s patent was based on small differences in the spacing between electrodes but did not define the difference in spacing. Biosig’s patent also purported to eliminate noise signals during the process of detecting a user’s heart rate. After Nautilus developed a new heart monitor, Biosig sued Nautilus alleging that Nautilus infringed its patent. Nautilus filed a summary judgment seeking to have the patent held invalid because it was vague and legally “indefinite.” The district court granted Biosig’s motion but the Federal Circuit reversed.

Under the “insolubly ambiguous” test, patents were upheld even when an individual patent was capable of more than one interpretation. The insolubly ambiguous test impacted a variety of healthcare devices and prescription drugs resulting in higher costs to consumers.  The Supreme Court held that the Federal Circuit’s “insolubly ambiguous” test was wrong, in that it would create “powerful incentives to inject ambiguity” into patent claims. In place of the ‘insolubly ambiguous’ standard, the Court held that “a patent is invalid for indefiniteness if its claims, read in light of the specification delineating the patent, and the prosecu¬tion history, fail to inform, with reasonable certainty, those skilled in the art about the scope of the invention.”

AARP Foundation Litigation attorneys filed AARP’s friend-of-the-court brief. Citing Supreme Court precedent, the brief pointed out that the public has a paramount interest in seeing that patent monopolies are kept within their legitimate scope; that the “insolubly ambiguous” test has been used to exclude competing hearing aid products to the detriment of consumers; and that allowing vague or ambiguous patents has limited competition in healthcare beyond hearing aids. The “insolubly ambiguous” test has increased patent litigation the cost of which is ultimately paid by consumers.

The U.S. Supreme Court agreed, throwing out the “insolubly ambiguous” test and demanding more clarity for patents.

What’s at Stake

When patents are improperly granted the cost of medical devices such as hearing aids and prescription drugs are elevated to the detriment of individuals and the general public. Ambiguous patents can be harmful by giving the patentee an unreasonably large monopoly to the detriment of the public. Ambiguous patents also impede innovation and encourage costly litigation when the scope of a particular patent is not clear.

Case Status

Nautilus, Inc. v. Biosig Instruments was decided by the U.S. Supreme Court.

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Legal Cases

Find cases in which AFL has advocated in courts nationwide for the rights of older persons, and filed AARP’s amicus curiae (“friend of the court”) briefs that help courts decide precedent-setting cases. The cases within the drop-down categories below are in alphabetical order for ease of searching.

Strengthening Law and Policy through
Legal Advocacy

Our legal advocacy initiatives  - conducted by AARP Foundation Litigation (AFL) - reflect nearly 20 years of work in federal and state courts across the country. Through our efforts, we support the Foundation’s four impact areas: Tackling Senior Hunger, Paving the Way to Stable Income, assuring the adequacy and availability of Safe and Afffordable Housing and Reconnecting People to Families and Communities, and ensure that those 50 and older have a voice in the laws and policies that affect their daily lives.