A person infringes another’s trademark through unauthorized use of that trademark or service mark (or by using a substantially similar mark) on competing or related goods and services. The success of a lawsuit to stop the infringement turns on whether the defendant's use causes a likelihood of confusion in the average consumer. If a court determines that confusion is likely, the owner of the original mark can prevent the second user's use of the infringing mark and sometimes collect damages.
For example, a foundational Supreme Court case on common law trademark infringement, McLean v. Fleming, held: “[m]uch must depend, in every case, upon the appearance and special characteristics of the entire device; but it is safe to declare, as a general rule, that exact similitude is not required to constitute an infringement or to entitle the complaining party to protection. If the form, marks, contents, words, or the special arrangement of the same, or the general appearance of the alleged infringer's device, is such as would be likely to mislead one in the ordinary course of purchasing the goods, and induce him to suppose that he was purchasing the genuine article, then the similtude is such as entitles the injured party to equitable protection, if he takes seasonable measures to assert his rights, and to prevent their continued invasion.” In that case, the Court found trademark infringement for a pill which, not identical to a trademarked pill, was so substantially similar that the Court found it was “calculated to mislead and deceive.”
Under the modern federal statutory regime, the Lanham Act governs federal trademarks, and allows an infringement action where any person, without the consent of the registrant, “use in commerce any reproduction, counterfeit, copy, or colorable imitation of a registered mark in connection with the sale, offering for sale, distribution, or advertising of any goods or services on or in connection with which such use is likely to cause confusion, or to cause mistake, or to deceive; or reproduce, counterfeit, copy, or colorably imitate a registered mark and apply such reproduction, counterfeit, copy, or colorable imitation to labels, signs, prints, packages, wrappers, receptacles or advertisements intended to be used in commerce upon or in connection with the sale, offering for sale, distribution, or advertising of goods or services on or in connection with which such use is likely to cause confusion, or to cause mistake, or to deceive.” While injunctive relief for the victim of trademark infringement is available, the Lanham Act takes steps to limit the injunctive actions courts may take. For example, in the case that the alleged infringer only prints the mark, the only injunctive relief available is to prevent future printing.
[Last updated in December of 2020 by the Wex Definitions Team]