Week 2 - Definiteness

Definiteness and two purposes in Nautilus v. Biosig

Patent law requires claims to be clear and distinct so competitors have notice of the boundaries of the property rights. This clarity also helps set the new invention apart from prior art.

Rejection of the Old Ambiguity Standard and New Standard

Supreme Court threw out the old rule that allowed patent claims as long as they were not "insolubly ambiguous". Instead, claims are invalid if they fail to inform experts about the scope of the invention with reasonable certainty in light of the specification and prosecution history.

Section 112 of Patent Act Definitenesss Requirement

requires one or more claims to particularly pointing out and distinctly claiming the subject matter that the inventor regards as their invention,

Background of Nautilus Patent

The patent in dispute involves an exercise heart-rate monitor designed to overcome electrical interference from muscle movements. Muscle signals often mask heart signals, making accurate heart-rate readings difficult during workouts.

How the Invention Solves Muscle Interference: The patented device takes advantage of ECG polarity differences between heart signals and muscle signals from opposite hands. By subtracting EMG identical muscle signals from both hands, the device filters out interference and reveals the heart signal.

Physical Configuration of the Device: The patent describes a hollow cylindrical bar that a user grips with both hands. Each hand touches two specific electrodes, categorized as one "live" electrode and one "common" electrode.

Details of Claim 1: Claim 1 outlines a heart monitor built into a bar with display screens, circuitry, and spaced-apart electrodes. It requires muscle signals from both hands to be equal so the amplifier can cancel them out completely.

Procedural Posture

Biosig sued Nautilus for selling exercise equipment containing its patented technology without a license. Biosig claimed that Nautilus continued this unauthorized use after acquiring the StairMaster brand.

Patent Office Reexamination: Nautilus asked the patent office to reexamine the patent against older similar devices. Biosig successfully defended its patent by showing that experts could find the proper electrode spacing through basic trial and error.

District Court Claim Interpretation: During the resumed lawsuit, the court focused on defining what "spaced relationship" meant for the electrodes. The judge defined it as a fixed spatial arrangement between electrodes without specifying exact physical measurements.Nautilus argued that the judge's definition was too vague and made the patent indefinite. The district court agreed, ruling that the patent failed to give clear guidance on exact spacing distances.

Appeals Court Reversal: The Federal Circuit reversed the decision, stating claims are only indefinite if they are "insolubly ambiguous". They reasoned that experts would naturally know the space must fit within a user's hand size without being infinitesimally small.


The Supreme Court declined to decide the final validity of the specific patent itself. Instead, it sent the case back to the Federal Circuit to apply the new "reasonable certainty" standard.

Dispute by Parties

Disagreements over Acceptable Imprecision: Nautilus argued that any claim with multiple reasonable interpretations is invalid for ambiguity. Biosig contended that a patent only needs to provide fair, reasonable notice of its boundaries.

Agreed Points of Law: Both parties agreed that clarity must be judged from the perspective of an expert in the field when the patent was filed. They also agreed that claims must be read alongside the patent's full description and history.

Supreme Court’s view of 112 definiteness

Balancing Innovation and Language Limits: Patent law must balance the limited nature of human language with the need for clear rules. A small amount of uncertainty is tolerated so inventors are not discouraged from creating new things.

Protecting the Public from Uncertainty: Patents must be clear enough to warn the public about what ideas are off-limits. Vague claims create unfair uncertainty that discourages other companies from experimenting

The Reasonable Certainty Rule

The Supreme Court ruled that claims must inform experts about the invention's scope with reasonable certainty in light of the specification and prosecution history. This standard demands meaningful clarity while accepting that absolute perfection in wording is impossible.

Why the “Insolubly Ambiguous" Test was flawed

The Supreme Court found the Federal Circuit's "insolubly ambiguous" standard too permissive and confusing. Lower courts cannot accept vague claims just because a judge might eventually guess a potential meaning

Rejection of Permissive Terminology: Even if the Federal Circuit meant well, using words like "insolubly ambiguous" creates legal confusion. The Supreme Court insisted that lower courts must use the proper, strict standard for clarity.

Definiteness Rationale

Primary: Give notice of what claim is
Secondary: to allow determination of invention’s patentability (metes and bounds)

Niazi v. St. Jude Medical Patent Background

In resynchronization therapy, placing wires in heart veins can be difficult due to tight acute angles and changing heart structures due to heart failure. The inventor solved this by creating a double catheter (tube) system that inserts leads more easily without excessive manipulation.

Procedural Posture

The trial court originally invalidated the patent claims as indefinite. It decided that descriptive words like "resilient" and "pliable" were too vague to be legal.

The Federal Circuit disagreed with the trial court's invalidation of the claims. It reversed the decision, holding that the terms were sufficiently clear to experts.

Purpose of Clear Notice and Definiteness Standard

A patent claim is indefinite only if it fails to inform skilled experts of its scope with reasonable certainty. Clear claims protect the public by clearly marking what actions would infringe on the patent. While absolute precision is not required, the description must give clear, fair warning.

Use of Descriptive Words: Inventors do not need to use exact mathematical numbers to create a clear patent claim. Descriptive words and terms of degree are acceptable if context gives enough certainty to experts.

Broadness versus Indefiniteness: A patent claim is not invalid simply because it covers a broad range of products. The true legal test is whether the phrasing clearly tells experts what is covered and what is not.

Examples of Definite Claims with objective terms despite being descriptive

(Sonix): In Sonix, the phrase "visually negligible" was ruled clear because it relied on standard human vision as a baseline. The patent provided concrete examples showing what the term meant in practice.

Example of Intrinsic Evidence (Enzo): In Enzo, the phrase "not interfering substantially" was found sufficiently clear. The patent contained clear examples in dependent claims that gave experts exact guideposts to follow.

Examples of Claims with purely subjective terms

(Datamize): Conversely, terms like "aesthetically pleasing" are invalid because they depend on personal opinion. Without an objective standard or measuring anchor, claims cannot be legally definite.

(Intellectual Ventures): The term "QoS requirements" was declared invalid because its meaning varied based on individual user preferences. Because it depended on subjective opinions, experts could not determine its exact boundaries.

Requirement for Objective Boundaries

Descriptive claim terms must always offer objective boundaries within the context of the invention. Courts look at the claims, specification, and prosecution history to locate these boundaries.

Objective Boundaries in Niazi: Together, the claim text and written description offer concrete, objective boundaries for both catheter parts. Unlike purely subjective phrases, these terms do not change based on who reads them

Guidance for the Term "Resilient"

The claim language explains that the outer catheter needs "shape memory" and stiffness to stay clear. Dependent claims also list specific resilient materials like braided silastic.The description explains that the outer tube uses a braided design to return to its original shape. This provides clear information to experts on how to select appropriate materials.

Guidance for the Term "Pliable"

The description contrasts the outer tube by giving an example of a inner catheter made of soft silicone, says it “is constructed of a more pliable, soft material.” It lacks longitudinal braiding, making it softer and far more flexible than the outer tube.

Support from Extrinsic Evidence

Dictionary definitions confirm that "resilient" means returning to shape and "pliable" means easily bent. These standard definitions show that experts understand what both words mean.

Why Court rejected St.Jude’s argument

The court rejected St. Jude's argument that a sentence about catheter flexibility created confusion. Despite using language that depicted byoth catheters having stiffness and flexibility, reading the whole patent makes clear that the outer tube is simply stiffer than the inner tube.

Class notes

Patent Litigation: Are the claims valid, then go to infringement

Definiteness is a matter of law, de novo so judge does not have to give deference to district court

“about” “substantially” “around” targeted for definiteness

Law v. Fact is based on tradition: Is it something given to jury

Enablement and Definitness: matter of law

Written Description: Matter of fact