Currently, flag burning is not illegal in the United States. The Supreme Court of the United States in its decision from 1969 has ruled that the burning of the flag is protected by the First Amendment. However, the person who burnt the flag can be found guilty of a misdemeanor for starting a fire without a permit.
Interesting that the burning of the flag has been against the law until 1969. The first U.S. Supreme Court ruling on flag desecration was passed in 1907 in Halter vs. Nebraska case. Most early flag desecration statutes prohibited burning a flag or any other ways of disrespecting the flag. Later, in 1968, Congress responded to the burning of the American flag in the Central Park as the protest against the Vietnam War by passing the Federal Flag Desecration Law. This law prohibited any display of “contempt” directed against the flag. Thus, burning of the American flag had been illegal until 1969 when the Supreme Court ruled the decision to award the First Amendment protection to the burning of the flag.
Furthermore, in a few court cases it has been declared that it is only illegal to burn the US flag if the flag would be stolen. In fact, burning the flag is one of approved ways to destroy a too worn or torn flag.
For the past 20 years, the Congress has made seven attempts to overrule the Supreme Court decision regarding the burning of the American flag by passing a constitutional amendment that had an exception to the First Amendment and allowed the government to ban flag desecration. The Amendment was first proposed in 1990 but failed to receive the required two-thirds majority votes of the House. After 1994, when the Republicans took over the Congress, the Amendment has consistently passed in the House but failed in the Senate.