DeRay Mckesson organized a protest in Baton Rouge after a police shooting. During efforts to clear protesters from a highway, an unidentified person threw a concrete object that seriously injured an officer. The officer sued Mckesson under Louisiana tort law. The Supreme Court of the United States vacated the Fifth Circuit’s judgment and remanded. The Court held that the Fifth Circuit should not have resolved the unsettled state-law question without first seeking guidance from the Louisiana Supreme Court on potentially controlling Louisiana law. The Court expressed no view on the merits of the tort claim or on other issues the lower court might address. The decision recognized that the dispute implicated both uncertain state-law principles and important First Amendment concerns. Justice Thomas dissented, and Justice Barrett did not participate.