[osreb]

Myth #5: It's against the law to burn the American flag
In the landmark case Texas v. Johnson in 1989, the Supreme Court ruled that desecrating the American flag is a form of speech protected by the First Amendment. Defendant Gregory Lee Johnson had burned a flag in an act of protest at the 1984 Republican National Convention in Dallas. Prior to that ruling it was, indeed, illegal to burn the flag.
Subsequent efforts on the judicial and legislative fronts to make flag burning illegal again have failed.