The internet, social media, and global commerce continue to spark phenomenal growth in the scope and importance of trademark and unfair competition law. At the same time, constitutional issues—pertaining to the Commerce Clause, the Patent and Copyright Clause, the Supremacy Clause, and the First Amendment—reshape trademark and unfair competition law and fuel influential debates in the academic literature. The many new decisions in this edition, including the continuing evolution of First Amendment analysis regarding permitted versus prohibited trademark registrations in Matal v. Tam, reflect these important developments. This textbook delineates the principal issues and provides a synthesis of this rapidly evolving area of law.