Illinois Upholds Qualitative Patent Claims Against Indefiniteness Challenge

The Northern District of Illinois granted a summary judgment of no invalidity based on indefiniteness on May 7, 2026, in the case of Xodus Medical Inc. Et al. V. U.S. Surgitech, Inc. The court ruled that qualitative language used in patent claims can be sufficiently definite if it provides an understandable boundary tied to a practical result.

The legal dispute centered on patents for devices and methods intended to secure patients on tilted surgical tables to reduce slippage. The defendant, U.S. Surgitech, Inc., argued that specific claim language within these patents was too vague to be enforceable, which would render the claims invalid under patent law.

The challenged language required a component to move sufficiently slow to maintain a depression for a desired period. U.S. Surgitech, Inc. Contended that the phrases sufficiently slow and desired period were inherently subjective and failed to provide a skilled artisan with reasonable certainty regarding the scope of the invention.

In its decision, the court disagreed that this qualitative language crossed the threshold into impermissible vagueness. The court found that the terms were definite when viewed in the context of the surrounding claim language and the patent specification.

The court distinguished the phrases in this case from open-ended comparative terms, such as better or improved, which typically lack a baseline for comparison. Instead, the court determined that the claim set a qualitative requirement tied to a functional outcome: the maintenance of a depression for as long as necessary.

Regarding the phrase desired period, the court explained that a skilled user would understand this as the time necessary to keep a patient stable during a procedure or a change in position. The court noted that while this duration might vary from case to case, such variability does not automatically make a claim indefinite.

The ruling emphasizes that precision in patent drafting is important, but the context of the claim and the practical application of the invention are also critical factors in determining definiteness.

For patent owners, the decision indicates that user-centered, outcome-oriented language may withstand challenges of indefiniteness. For accused infringers, the ruling suggests that challenging qualitative terms requires more than demonstrating that the terms may result in variability.