In U.S. law, the expression “secondary liability” is an umbrella term encompassing a number of different types of trademark infringement claims, 1 but its essential meaning is that liability does not turn on the defendant itself using the plaintiff’s mark. Rather, in such cases, the defendant is held responsible for the infringements occasioned by a third party’s use of the plaintiff’s mark. Trademark owners might strategically prefer to bring a secondary liability claim instead of suing the third party infringer. A secondary infringement action may increase efficiency by allowing the mark owner to secure, in a single proceeding, relief against a party whose conduct is simultaneously enabling multiple acts of infringement by a number of primary infringers.
The advent of the Internet has only enhanced some of these strategic benefits. The efficiency gains are magnified substantially when the number of infringements to which the secondary liability defendant contributes are multiplied many times over. And looking forward, the secondary liability action might shift some of the costs of trademark enforcement to intermediaries. This occurs whether the mark owner directly secures relief from a court that requires an intermediary to undertake certain detection and prevention measures, or because the intermediary adjusts its practices to be more conservative in light of an award made against it under principles of secondary liability. This means that a finding of secondary liability may enable mark owners to affect the future structure of business models employed by intermediaries and the direction of technological development considered by intermediaries.