Background
Niazi Licensing Corporation holds U.S. Patent No. 6,638,268, which covers a cardiac catheter for accessing the coronary sinus of the heart to deliver pacing therapy to patients with heart failure. The patent claims a catheter with an “outer catheter” described as “resilient” and an “inner catheter” described as “pliable” — two terms that characterize the physical properties of the catheter components but do not specify precise numerical values.
St. Jude Medical moved for summary judgment that the patent claims were invalid for indefiniteness under 35 U.S.C. § 112. St. Jude argued that “resilient” and “pliable” were purely relative terms with no objective meaning, making it impossible for a person of ordinary skill in the art to determine whether the claimed properties were satisfied. The District of Minnesota agreed, holding the terms indefinite, and Niazi appealed.
The Court’s Holding
The Federal Circuit reversed. Writing for the court, Judge Stoll applied the Nautilus definiteness standard — which requires that claims inform those skilled in the art about the scope of the invention “with reasonable certainty” — and held that “resilient” and “pliable” satisfied that standard in the context of the ‘268 patent.
The court rejected the proposition that relative or flexible terms are categorically indefinite merely because they describe a property that exists on a spectrum. Many ordinary and recognized terms in engineering, medicine, and science describe functional properties without specifying precise numerical boundaries — terms like “strong,” “flexible,” “durable,” and similar descriptors are routinely used in claims without being considered indefinite. Whether such terms provide reasonable certainty depends on context: the specification, prosecution history, and what a skilled artisan would understand.
Here, the patent specification provided meaningful context for both terms. A person skilled in the art of catheter design would understand the relevant range of resilience and pliability from the functional requirements described in the patent and the nature of the technology. Because the specification provided objective boundaries — even without specifying a precise numerical threshold — the terms were not indefinite. The Federal Circuit reversed the indefiniteness ruling and remanded for further proceedings.
Key Takeaways
- Claim terms that admit of degrees or describe a spectrum of properties are not automatically indefinite; the Nautilus standard requires only reasonable certainty, not mathematical precision.
- Relative terms like “resilient,” “pliable,” “flexible,” or “strong” can satisfy definiteness requirements when the specification provides sufficient context for a skilled artisan to understand the scope of the claim.
- The definiteness inquiry is contextual — courts must assess what a person of ordinary skill in the art would understand from the full disclosure, not just the claim language in isolation.
- Patent drafters using relative terms in claims should include examples, functional descriptions, or comparative language in the specification to establish objective boundaries for those terms.
Why It Matters
Niazi v. St. Jude Medical is an important reminder that the definiteness requirement under § 112 does not demand that every claim term be reducible to a precise numerical value or bright-line threshold. Many valuable inventions — particularly in medical devices, materials science, and manufacturing — are naturally described in terms of relative properties like resilience, flexibility, or strength. Requiring numerical precision in all such claims would make large categories of legitimate inventions unpatenable.
The decision reinforces that Nautilus — while establishing a meaningful definiteness standard — does not sweep away the settled practice of claiming inventions using functional or relative descriptors that skilled artisans understand. For patent prosecutors and litigators, the case supports the practice of using well-understood engineering and materials terms in claims, backed by context-rich specifications that orient a skilled reader to the relevant range of those properties.