President-elect Donald Trump took to his Twitter account early Tuesday to announce that the burning of the U.S. flag is illegal and those found doing so will face punishment. The Republican said that those who burn the American flag will lose their citizenship or face one year in jail.

Using the flag as a symbol of protest is an American tradition. During protests, the country has witnessed the burning of the flag as protestors vent out their anger as a mode of free speech.

In 2005, Hillary Clinton co-sponsored a bill that would make burning the American flag a criminal act punishable by one year in prison and a $100,000 fine.

Despite the American Civil Liberties Union (ACLU) calling the burning of the flag offensive, it is not illegal or unconstitutional.

The first flag burning case in the Supreme Court was Texas v. Johnson. On June 21, 1989, a deeply divided court voted 5-4 in favor of Johnson, a protester in Texas who burned the U.S. flag. Johnson’s actions, the majority argued, were symbolic speech, political in nature and could be expressed even if it upset those who disagreed with him.

In reaction to the Johnson decision, which only applied to the state of Texas, Congress passed an anti-flag burning law called the Flag Protection Act of 1989.

However, in 1990, the Court struck down that law as unconstitutional in a second case, United States v. Eichman.