In Biosig Instruments, Inc. v. Nautilus Inc., the Federal Circuit reversed the district court’s finding that the claims at issue were invalid as indefinite, because the claims were not “insolubly ambiguous.” This case underscores the difficulty of challenging a patent under 35 USC § 112, second paragraph.
The Patent At Issue
The patent at issue was Biosig’s U.S. Patent 5,337,753, directed to a heart rate monitor associated with an exercise apparatus and/or exercise procedures. As set forth in the Federal Circuit decision, the claimed heart rate monitor is said to “eliminate signals given off by skeletal muscles (“electromyogram” or “EMG” signals), which are brought about when users move their arms or squeeze the monitor with their fingers.
Claim 1 recites:
A heart rate monitor for use by a user in association with exercise apparatus and/or exercise procedures, comprising[:]
an elongate member;
electronic circuitry including a difference amplifier having a first input terminal of a first polarity and a second input terminal of a second polarity opposite to said first polarity;
said elongate member comprising a first half and a second half;
a first live electrode and a first common electrode mounted on said first half in spaced relationship with each other;
a second live electrode and a second common electrode mounted on said second half in spaced relationship with each other;
said first and second common electrodes being connected to each other and to a point of common potential;
said first live electrode being connected to said first terminal of said difference amplifier and said second live electrode being connected to said second terminal of said difference amplifier;
a display device disposed on said elongate member;
wherein, said elongate member is held by said user with one hand of the user on said first half contacting said first live electrode and said first common electrode, and with the other hand of the user on said second half contacting said second live electrode and said second common electrode;
whereby, a first electromyogram signal will be detected between said first live electrode and said first common electrode, and a second electromyogram signal, of substantially equal magnitude and phase to said first electromyogram signal will be detected between said second live electrode and said second common electrode;
so that, when said first electromyogram signal is applied to said first terminal and said second electromyogram signal is applied to said second terminal, the first and second electromyogram signals will be subtracted from each other to produce a substantially zero electromyogram signal at the output of said difference amplifier;
and whereby a first electrocardiograph signal will be detected between said first live electrode and said first common electrode and a second electrocardiograph signal, of substantially equal magnitude but of opposite phase to said first electrocardiograph signal will be detected between said second live electrode and said second common electrode;
so that, when said first electrocardiograph signal is applied to said first terminal and said second electrocardiograph signal is applied to said second terminal, the first and second electrocardiograph signals will be added to each other to produce a non-zero electrocardiograph signal at the output of said difference amplifier;
means for measuring time intervals between heart pulses on detected electrocardiograph signal;
means for calculating the heart rate of said user using said measure time intervals;
said means for calculating being connected to said display device;
whereby, the heart rate of said user is displayed on said display device.
The alleged indefiniteness relates to the physical configuration of the electrodes, as reflected in the “spaced relationship” claim language.
The District Court’s Indefiniteness Determination
As summarized by the Federal Circuit, the district court construed the term “spaced relationship” to mean that “there is a defined relationship between the live electrode and the common electrode on one side of the cylindrical bar and the same or a different defined relationship between the live electrode and the common electrode on the other side of the cylindrical bar.”
As the Federal Circuit noted:
Notwithstanding that this disputed term was amenable to construction, the district court determined that the term was indefinite. Specifically, the district court stated that “a spaced relationship did not tell me or anyone what precisely the space should be . . . . Not even any parameters as to what the space should be . . . . Nor whether the spaced relationship on the left side should be the same as the spaced relationship on the right side.”
Thus, the district court found that the claims were invalid as indefinite under 35 USC § 112, second paragraph.
The Federal Circuit Decision
The Federal Circuit decision notes that indefiniteness is an issue of law that it “reviews without deference.” The court stated the legal standard as follows:
A claim is indefinite only when it is “not amenable to construction” or “insolubly ambiguous.”
The court also noted that “[g]eneral principles of claim construction apply when determining indefiniteness.” Thus, when evaluating a claim for indefiniteness, the court primarily considers “the claim language, the specification, and the prosecution history,” and also “may consider certain extrinsic evidence.” The court explained further:
When a “word of degree” is used, the court must determine whether the patent provides “some standard for measuring that degree.” …. Similarly, when a claim limitation is defined in “purely functional terms,” a determination of whether the limitation is sufficiently definite is “highly dependent on context (e.g., the disclosure in the specification and the knowledge of a person of ordinary skill in the relevant art . . . ).”
[W]e have not insisted that claims be plain on their face in order to avoid a determination of invalidity for indefiniteness.” …. In addition, “[p]rovided that the claims are enabled, and no undue experimentation is required, the fact that some experimentation may be necessary to determine the scope of the claims does not render the claims indefinite.” …. Therefore, objections relating to the mere fact that there may be some need for experimentation to determine the scope of the claims carry little weight.
Turning to the case at hand, the Federal Circuit noted that “the district court is correct that the specification of the ’753 patent does not specifically define ‘spaced relationship’ with actual parameters, e.g., that the space between the live and common electrodes is one inch.” Nevertheless, the Federal Circuit found the “claim language, specification, and … figures” of the ‘753 patent to “provide sufficient clarity to skilled artisans as to the bounds of this disputed term.”
In particular, the Federal Circuit noted:
[O]n the one hand, the distance between the live electrode and the common 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.
Thus, the Federal Circuit determined that “the ’753 patent discloses certain inherent parameters of the claimed apparatus, which to a skilled artisan may be sufficient to understand the metes and bounds of ‘spaced relationship.’” The court also found guidance in the reexamination prosecution history and extrinsic evidence that supported the definiteness of claims.
The court concluded:
[T]he record shows that the variables here, including the spacing, size, shape, and material affecting the “spaced relationship” between the electrodes, can be determined by those skilled in the art. Thus, “spaced relationship” cannot be said to be insolubly ambiguous.
The Federal Circuit therefore reversed the district court’s invalidity judgment and remanded for further proceedings.