The latest in a string of controversial tweets by President-elect Donald Trump suggests people who burn the American flag should be locked up or lose their citizenship.

"Nobody should be allowed to burn the American flag — if they do, there must be consequences — perhaps loss of citizenship or year in jail," Trump wrote Tuesday morning. 

His tweet comes after weeks of protests on college campuses and in cities around the nation in response to Trump winning the presidential election.

Among those, students at American University burned several flags at their Washington, D.C., campus. At a college in Massachusetts, the school's board removed the star-spangled banner from the center of campus after students burned it on Veterans Day.

Though offensive to many, these instances are not punishable by law, despite what the president-elect deems appropriate.

In 2006, Congress tried and failed to pass a law that would ban desecration of the American flag by amending the Constitution. The Washington Post reported at the time that the 66-to-34 Senate vote fell short of the two-thirds majority required to approve the amendment.

At the time, then-Sen. Hillary Clinton, Democrat of New York, along with then-Sen. Lincoln Chafee of Rhode Island (a Republican at the time and now a Democrat) and current Senate Majority Leader Mitch McConnell, a Kentucky Republican, were among those who voted against the measure. The New York Times reported in 2006, however, that Clinton was sponsoring similar legislation that did not require a constitutional amendment.

But even before then, the Supreme Court ruled twice that burning the flag is a protected form of free speech.

In Texas v. Johnson and United States v. Eichmanin 1989 and 1990, respectively, the high court knocked down laws that banned flag desecration. In both, the late Justice Antonin Scalia — to whose seat Trump will appoint a replacement — sided to protect the right to burn the American flag.

"We have a First Amendment which says that the right of free speech shall not be abridged, and it is addressed in particular to speech critical of the government," Scalia said in a 2012 interview with CNN. "That was the main kind of speech that tyrants would seek to oppress."