No Numbers Required: N.D. Illinois Upholds “Qualitative” Patent Claims Against Indefiniteness Challenge

Why It Matters

The ruling clarifies that patent claims need not include exact numbers if the specification provides objective context, easing drafting constraints and reducing indefiniteness vulnerability for medical‑device innovators.

Key Takeaways

• Court upheld qualitative claim terms as definite using intrinsic record
• “Rate of recovery” defined by 2‑10 sec recovery band in specification
• “Substantial portion of holding forces” testable by tilting table without straps
• No expert testimony needed; indefiniteness requires objective criteria, not numerical thresholds
• Drafting tip: anchor qualitative descriptors with functional context and quantified examples

Pulse Analysis

In a January 2026 decision, the Northern District of Illinois tackled a classic § 112 indefiniteness challenge by focusing on the intrinsic record rather than demanding precise numerical limits. The court dissected three functional limitations in patents covering foam pads that secure patients on tilted surgical tables. By linking the phrase “desired period of time” to a measurable change in depression‑generating force and citing the specification’s explicit recovery‑time bands (50‑80 % in 2‑10 seconds, full recovery in 10‑35 seconds), the judge demonstrated that the claims provide a clear, objective reference point for a person of ordinary skill.

The ruling sends a clear signal to patent drafters: qualitative language is permissible when the specification supplies functional context, clear definitions, and concrete examples. Rather than embedding exact thresholds, practitioners can describe performance ranges or functional outcomes, provided they include testable methods—such as tilting a table without straps to assess whether the foam supplies a “substantial portion” of holding force. This approach not only streamlines claim drafting but also fortifies patents against indefiniteness attacks that rely on the absence of numerical precision.

For the broader medical‑device sector, the decision may encourage more innovative claim strategies that balance flexibility with defensibility. Companies can now leverage functional descriptors to capture a spectrum of embodiments without over‑specifying, while still satisfying legal standards. Legal teams should audit existing portfolios to ensure that qualitative terms are anchored by objective criteria, reducing litigation risk and preserving valuable IP assets in a competitive market.