Causal Nexus

A patentee must establish a causal nexus between irreparable harm and the infringing activity.

To satisfy the first eBay factor, the patentee must show that it is irreparably harmed by the infringement. This requires proof that a causal nexus relates the alleged harm to the alleged infringement. Apple Inc. v. Samsung Elecs. Co., 695 F.3d 1370, 1374 (Fed.Cir.2012) ("Apple II"). This just means that there must be proof that the infringement causes the harm.

— Apple Inc. v. Samsung Electronics Co., Ltd., 809 F. 3d 633, 639 (Fed. Cir. 2015).

The nexus requirement prevents injunctions from issuing in cases where harm is caused by factors other than infringement.

The causal nexus requirement ensures that an injunction is only entered against a defendant on account of a harm resulting from the defendant's wrongful conduct, not some other reason.

— Apple Inc. v. Samsung Electronics Co., Ltd., 809 F. 3d 633, 640 (Fed. Cir. 2015).

The nexus requirement may also act to prevent a patentee from misusing its patent rights for competitive advantage.

[T]he causal nexus inquiry … informs whether the patentee's allegations of irreparable harm are pertinent to the injunctive relief analysis, or whether the patentee seeks to leverage its patent for competitive gain beyond that which the inventive contribution and value of the patent warrant.

— Apple Inc. v. Samsung Electronics Co., Ltd., 695 F. 3d 1370, 1375 (Fed. Cir. 2012).

The nexus requirement applies equally in cases where an injunction is sought on an infringing feature.

[A] causal nexus linking the harm and the infringing acts must be established regardless of whether the injunction is sought for an entire product or is narrowly limited to particular features.

— Apple Inc. v. Samsung Electronics Co., Ltd., 809 F. 3d 633, 640 (Fed. Cir. 2015).

The patentee must show that infringement is the driving force behind the harm they seek to establish.

The relevant question is not whether there is some causal relationship between the asserted injury and the infringing conduct, but to what extent the harm resulting from selling the accused product can be ascribed to the infringement.

— Apple Inc. v. Samsung Electronics Co., Ltd., 695 F. 3d 1370, 1375 (Fed. Cir. 2012).