IP Law Daily, PATENT—N.D. Cal.: Preliminary injunction denied in thrombectomy system dispute, (Sep 30, 2025)

By Kevin M. Finson, J.D.

There was not a likelihood of success on the merits in an infringement case because the defendant raised serious questions of patent validity and because there was no risk of irreparable harm with any nexus to the infringement.

A manufacturer of medical devices used to extract blood clots was not entitled to a preliminary injunction forcing a competitor to cease sales, the U.S. District Court in San Jose has held. The manufacturer failed to show that any of the traditional injunction factors weighed in favor of an injunction (Inari Medical, Inc. v. Imperative Care, Inc., No. 5:24-cv-03117-EKL (N.D. Cal. Sept. 29, 2025)).

Inari Medical, Inc. (Inari) was the owner of U.S. Patents Nos. 11,844,921 (the ’921 patent) and 11,974,910 (the ’910 patent), both of which related to medical devices used by physicians to remove blood clots from a patient’s veins. Inari brought suit for infringement against Imperative Care, Inc. (Imperative), a competing seller of thrombectomy devices. Inari petitioned for a preliminary injunction requiring that Imperative cease making, using, and selling its devices in the United States. The court considered the Winter preliminary injunction factors.

Likelihood of success on the merits. The court noted that, in a parallel proceeding before the Patent Trial and Appeal Board, inter partes review had been instituted as to the validity of related patent claims on obviousness grounds. The court found that the PTAB decision was strong circumstantial evidence against a likelihood of success on the merits and also considered independently the prior art at issue in that case and found that Imperative had raised substantial questions of obviousness or anticipation, which Inari did not show lacked substantial merit.

Irreparable harm. The court found that the harm which could be suffered by Inari in the absence of an injunction was monetary in nature and could likely be remedied by monetary damages. There was not sufficient evidence to suggest that Inari would suffer a permanent loss of market share or price erosion. Additionally, the court found that the harm lacked a nexus to the actual patent infringement because the patent claims asserted related to valves which were concealed within the device and not readily apparent to the purchasers, and which did not appear to have a significant effect on a consumer’s choice between the parties’ respective devices.

Balance of hardships. The proposed injunction would bar Imperative’s only product in the mechanical thrombectomy market and would accordingly cause significant hardship. While the denial of the injunction would cause Inari to suffer competition from Imperative, the court had already determined that this harm was not irreparable.

Public interest. The court found this factor was neutral. While the public interest usually favored enforcement of patent rights, this interest was limited by the serious questions of validity raised about the patent claims.

The court denied the motion for a preliminary injunction.

The Case is No. 5:24-cv-03117-EKL.

Judge: Lee, E.

Attorneys: Ramsey M. Al-Salam (Perkins Coie LLP) for Inari Medical, Inc. Joshua Jan Stowell (Knobbe Martens Olson and Bear, LLP) for Imperative Care, Inc.

Companies: Inari Medical, Inc.; Imperative Care, Inc.

Cases: Patent CaliforniaNews