Abstract: False advertising law has largely escaped constitutional scrutiny because courts consider false or misleading commercial speech outside the protection of the First Amendment. Even moderate First Amendment protection for truthful commercial speech, however, requires some constitutional policing of the line between truth and falsity. Current enforcement of false advertising law, whether administrative, as with the FDA's regulation of drug-related speech, or judicial, as with Lanham Act suits brought by private parties, is ill-equipped to deal with First Amendment doctrine's very different concerns, rules, and presumptions. This contribution to the symposium will explore some of the ways in which the First Amendment and trademark law - a type of false advertising law - differ in approach. Unlike most treatments of the subject through a First Amendment lens, this one does not begin with the presumption that the standard First Amendment approach is superior.