15.5 Trademark Liability-Theories and Policies is a legal concept related to the protection of brand names, logos, and other trademarks. It deals with the legal remedies available to trademark owners when their marks are infringed upon and the potential liabilities of the infringed. Generally, there are two theories of trademark liability: the traditional common law action for trademark infringement and the modern statutory action for trademark dilution. The traditional common law action for trademark infringement is based on a legal principle known as the “likelihood of confusion” test. Under this test, a trademark owner can sue a third party for using a mark that is confusingly similar to their own mark. In order to establish a trademark infringement claim, a plaintiff must prove that the defendant’s use of the mark is likely to cause confusion among consumers and that the defendant’s use has damaged the plaintiff’s goodwill and reputation. The modern statutory action for trademark dilution is a more expansive remedy than the traditional common law action for trademark infringement. Trademark dilution occurs when an infringed use a mark that is similar to a well-known mark, even if the use is not likely to cause confusion among consumers. The purpose of this remedy is to protect the owner of a famous mark from having their mark diminished or tarnished due to the unauthorized use of a similar mark. Overall, 15.5 Trademark Liability-Theories and Policies provide trademark owners with legal remedies when their marks are infringed upon. These remedies can be used to protect the owner’s goodwill and reputation and ensure that the value of their mark is not diminished by unauthorized third-party use.