States all over the world are enacting new laws that criminalize insults, and using existing insult laws with renewed vigour. In this article, we examine state practice, treaty provisions, and case law on insulting speech. We conclude that insulting speech is currently insufficiently protected under international law and regulated by confused case law and commentary. We explain that the three principal international treaties that regulate speech provide conflicting guidance on the right to insult in international law, and the treaty provisions have been interpreted in inconsistent ways by international courts and United Nations bodies. We conclude by recommending that international law should recognize a “right to insult” and, drawing on U.S. practice under the First Amendment, we propose eight recommendations to guide consideration of insulting speech in international law. These recommendations would promote coherence in international legal standards and offer greater protection to freedom of speech.