Words of Degree Are Not Automatically Indefinite: Niazi v. St. Jude Medical

Patent drafters reach constantly for words of degree (“resilient,” “pliable,” “substantially,” “about”) because real inventions resist hard numerical boundaries. For years, accused infringers have argued that such language is fatally vague. In Niazi Licensing Corp. v. St. Jude Medical S.C., Inc., 30 F.4th 1339 (Fed. Cir. 2022), the Federal Circuit pushed back, holding in an opinion by Judge Kara Stoll that relative terms are not automatically indefinite and that a patent’s own disclosures can supply the certainty the statute demands. Decided April 11, 2022, the decision is a useful modern marker of how far the definiteness requirement does, and does not, reach.

At a glance

• Case: Niazi Licensing Corp. v. St. Jude Medical S.C., Inc., No. 2021-1864, 30 F.4th 1339 (Fed. Cir. Apr. 11, 2022).
• Court: U.S. Court of Appeals for the Federal Circuit; opinion by Judge Stoll, joined by Judges Taranto and Bryson, on appeal from the District of Minnesota.
• Posture: Appeal from a judgment holding all but one asserted claim of U.S. Patent No. 6,638,268 invalid as indefinite, plus evidentiary and sanctions rulings.
• Holding: The terms “resilient” and “pliable” are definite when read against the intrinsic evidence; the indefiniteness judgment is reversed and remanded, while the expert-exclusion and sanctions rulings and the summary judgment of no induced infringement of claim 11 are affirmed.
• Significance: Confirmed that terms of degree are not inherently indefinite and clarified how the specification and dependent claims can rescue relative language under 35 U.S.C. 112.

The double-catheter invention

The ‘268 patent claims a double catheter designed to cannulate the coronary sinus (threading a vein of the heart) without the significant manipulation older single catheters required, an advance relevant to treating congestive heart failure. The design pairs an outer catheter described as “resilient” with an inner catheter described as “pliable,” so the stiffer outer member provides support and torque control while the softer inner member navigates delicate vessels. The District of Minnesota construed “resilient” and “pliable” as indefinite, reasoning that those relative terms gave no objective boundary, and on that basis held all but one of the asserted claims invalid. Because indefiniteness is a question the court resolves as a matter of law (informed by underlying facts), the ruling effectively gutted the patent before infringement was even reached.

Terms of degree under Nautilus

The governing standard comes from 35 U.S.C. 112, as interpreted by the Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc. (2014): a claim is indefinite only if, read in light of the specification and prosecution history, it fails to inform skilled artisans “about the scope of the invention with reasonable certainty.” Reasonable certainty, the Federal Circuit emphasized, is not absolute precision. Quoting Nautilus, the panel noted that the definiteness requirement “mandates clarity, while recognizing that absolute precision is unattainable,” and reaffirmed from its own precedent that “a patentee need not define his invention with mathematical precision in order to comply with the definiteness requirement.” The court has long accepted descriptive terms of degree so long as the intrinsic record supplies enough guidance. Judge Stoll framed the real problem with descriptive words not as their breadth (broad claims are a validity issue for other doctrines) but as whether the words leave a skilled reader genuinely unable to discern the claim’s boundaries.

Why “resilient” and “pliable” passed

Applying that standard, the panel found ample anchoring in the patent itself. For “resilient,” dependent claims supplied concrete examples of qualifying materials (such as “braided silastic”) and the written description explained that the outer catheter has a “braided design” and that its resilience provides for “torque control and stiffness,” giving skilled readers a recognizable class of structures. For “pliable,” the specification identified silicone as a suitable soft material for the inner catheter and explained that the inner catheter “has no longitudinal braiding, which makes it extremely flexible and able to conform to various shapes.” Read together, the intrinsic evidence let a person of ordinary skill understand which catheters were resilient (stiffer, braided, supportive) and which were pliable (softer, unbraided, conforming) with reasonable certainty. The court therefore reversed the indefiniteness holding as to claims 1, 10, 13-15, 18-19, and 23-27 and remanded so the district court could take up infringement of those claims and St. Jude’s remaining invalidity defenses.

A mixed result

The reversal on definiteness did not hand Niazi a win on the merits; it sent the revived claims back for further proceedings while everything else went St. Jude’s way. The Federal Circuit affirmed the district court’s evidentiary sanctions, which excluded portions of Niazi’s expert reports because the patentee had failed to disclose predicate facts during discovery, and affirmed the exclusion of part of the damages report as unreliable, along with monetary sanctions covering costs and fees tied to a motion to strike. On claim 11, the only asserted claim not held indefinite, the court disagreed with the district court’s constructions of two method steps but agreed with its constructions of two others and, crucially, agreed that Niazi had not met its burden to prove direct infringement, a necessary element of its inducement theory. It therefore affirmed summary judgment of no induced infringement of claim 11 without reaching Niazi’s arguments on specific intent. The lesson cuts two ways: careful drafting can defeat an indefiniteness attack, but litigation discipline in discovery and proof still decides who wins.

Open questions

• How much intrinsic support is enough? Niazi had dependent claims and specific material examples; the opinion leaves unclear how thin the disclosure can become before a term of degree tips into indefiniteness.
• What about terms with no exemplary structures? The decision turned partly on concrete examples like silastic and silicone; relative terms unmoored from any disclosed embodiment remain riskier.
• Where is the line between breadth and indefiniteness? The court insisted breadth alone is not the problem, but broad functional language continues to draw scrutiny under both Section 112 and eligibility doctrines.

Implications

• For patent drafters: Pair relative terms with concrete examples, material lists, and explanatory passages in the specification; dependent claims that name qualifying structures can be decisive evidence of definiteness.
• For accused infringers: An indefiniteness defense aimed at a single descriptive word is weak when the specification explains the term; aim instead at terms genuinely unsupported by the intrinsic record.
• For litigators: Discovery compliance matters as much as claim drafting. Niazi salvaged its claims but lost on infringement partly because key expert evidence was excluded as a sanction.
• For licensors and portfolio owners: Terms of degree remain usable and enforceable, but their durability depends on the quality of the written description supporting them.
• For trial courts: Definiteness must be assessed against the full intrinsic record, not by isolating a relative word and declaring it boundless.

Frequently asked questions

Does using a relative term like resilient make a patent claim indefinite? No. The Federal Circuit confirmed that terms of degree are not inherently indefinite. A claim is invalid for indefiniteness only if, read in light of the specification and prosecution history, it fails to inform a skilled person about the scope of the invention with reasonable certainty.

What is the legal standard for definiteness? Under 35 U.S.C. 112 and the Supreme Court’s 2014 Nautilus decision, a claim must inform those skilled in the art about the scope of the invention with reasonable certainty when read in light of the specification and prosecution history. Some uncertainty is tolerated; absolute precision is not required.

Did Niazi ultimately win the case? Only in part. The Federal Circuit reversed the indefiniteness ruling, revived most of the claims, and remanded them for the district court to decide infringement and St. Jude’s remaining invalidity defenses. But it affirmed the exclusion of portions of Niazi’s expert reports as a discovery sanction, the monetary sanctions, and summary judgment of no induced infringement of claim 11, the one claim that had survived indefiniteness below.

Authorities and sources

• Niazi Licensing Corp. v. St. Jude Medical S.C., Inc., No. 2021-1864, 30 F.4th 1339 (Fed. Cir. Apr. 11, 2022), slip opinion (court PDF): https://www.cafc.uscourts.gov/opinions-orders/21-1864.OPINION.4-11-2022_1934126.pdf
• Definiteness requirement, 35 U.S.C. 112 (Cornell LII): https://www.law.cornell.edu/uscode/text/35/112
• Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014) (Cornell LII): https://www.law.cornell.edu/supremecourt/text/13-369