The U.S. Supreme Court case Iancu v. Brunetti (2018) involved a dispute over trademark law and First Amendment rights to free speech. Erik Brunetti, founder of the clothing line FUCT, was denied federal registration for his brand by the United States Patent and Trademark Office (USPTO), citing that it violated the Lanham Act's prohibition on trademarks that consist of or comprise immoral or scandalous matter. The USPTO argued that "FUCT" was phonetically equivalent to a vulgar word and therefore unfit for protection under federal law. However, Brunetti contended this rejection infringed upon his First Amendment rights to freedom of speech. In its decision, the Supreme Court sided with Brunetti in a 6-3 ruling stating that prohibiting trademarks because they express offensive ideas violates the First Amendment as it discriminates based on viewpoint - an infringement upon free speech rights. This landmark ruling clarified how far protections for free expression extend into commercial activities like branding and advertising.

In the dissenting opinion for Iancu v. Brunetti, Justice Sotomayor, joined by Justice Breyer, argued that the majority's decision would lead to potentially harmful consequences. She expressed concern about opening public spaces to lewdness and vulgarity under the guise of free speech protections. The justices believed that there should be a balance between First Amendment rights and society's interest in maintaining a certain level of decency and respect in public discourse. They contended that refusing registration to obscene trademarks does not restrict anyone’s ability to express their ideas but merely declines to promote them through federally registered trademarks. Furthermore, they suggested an alternative interpretation of the statute at issue which could preserve its constitutionality while avoiding potential harm caused by offensive marks.