1932: Started in the late 1800s, efforts by all 50 states to pass laws outlawing the desecration of the flag succeed.

1968: Congress passes the first federal flag desecration law in the wake of a highly publicized Central Park flag burning incident in protest of the Vietnam War.

1969: The Supreme Court holds that New York could not convict a person based on his verbal remarks disparaging the flag.

1989: For the first time, the Supreme Court applies the First Amendment and protects flag burning. The court confirms that Texas acted unconstitutionally by making it a crime to desecrate or mistreat the flag.

Source: Committee on the Judiciary — Democratic Key Issues

http://www.house.gov/judiciary_democrats/dchrono.htm