Writing for the Court, Chief Justice Hughes held that California’s law was unconstitutional because it was too vague and too restrictive of free speech. Hughes acknowledged that the government has the right to limit speech in certain instances, writing that “[t]here is no question but that the State may thus provide for the punishment of those who indulge in utterances which incite to violence and crime and threaten the overthrow of organized government by unlawful means,” but that “[a] statute which upon its face, and authoritatively construed, is so vague and indefinite as to permit the punishment of the fair use of this opportunity is repugnant to the guaranty of liberty contained in the Fourteenth Amendment.”

Hughes found the section of the law which prohibited the display of a red flag as a “sign, symbol, or emblem of opposition to organized government” to be unconstitutional because it was too restrictive of free speech and it violated due process and under the Fourteenth Amendment. The other two provisions of the statute, which prohibited the flag’s display as an “invitation or stimulus to anarchistic action” or as an “aid to propaganda that is of a seditious character,” were both upheld as constitutional. On these provisions, Hughes reasoned that they served a legitimate government interest in protecting against incitements to violence. Despite the validity of two of the three provisions, Hughes reversed Stromberg’s conviction. This was also the first case in which the Court recognized constitutional protections for symbolic speech, such as Stromberg’s flag.