Texas v. Johnson was a 1989 ruling of the United States Supreme Court, that stated that the laws condemning the profanation of the national flag, then in force in forty-eight states, were inconsistent with the First Amendment and the Federal Constitution which prohibited Congress from restricting freedom of speech.
The protection provided by the First Amendment, in the opinion of the Court, does not end only on the spoken and written words. The Court therefore rejected the argument that ignition of a flag can not be characterized as speech (since the First Amendment protects only speech). What is important to characterize a process as a speech is the intention to transfer a certain message through it, so, in the case, the burning of the flag was admitted as a speech and, therefore, protected by the First Amendment.