“Nobody should be allowed to burn the American flag,” President-elect Donald Trump tweeted Tuesday. “If they do, there must be consequences — perhaps loss of citizenship or year in jail!”

“If I were king,” the late Supreme Court Justice Antonin Scalia once said in an interview, “I would not allow people to go about burning the American flag. However, we have a First Amendment, which says that the right of free speech shall not be abridged. … Burning the flag is a form of expression. Speech doesn’t just mean written words or oral words. … Burning a flag is a symbol that expresses an idea.”

Mr. Scalia was part of the 1989 Supreme Court majority that held that flag-burning was protected by the First Amendment. Revoking citizenship for flag-burning would be unconstitutional.

Mr. Scalia was no progressive, but a conservative icon. And Mr. Trump himself called Justice Scalia a “great judge.” “I am looking to appoint judges very much in the mold of Justice Scalia,” Mr. Trump said during the campaign.

Mr. Scalia was devoted to the First Amendment, as any great judge must be. He loved the flag, but he loved free speech, one of the principles for which the flag stands, more.

But Mr. Scalia was talking about more than that. He was pointing out that what he might personally wish were the case is not necessarily what the Constitution allows. And he, as a justice, was bound to rule according to what the Constitution said, not what he personally believed. We are a government of laws, not of men.

A president has a similar obligation to govern within the bounds of the Constitution. He is not a king.

No man or woman can be fully prepared for the presidency. Even Lincoln was not prepared, except in terms of temperament. The responsibility is out of scale with any other job. But a president must also learn that there are limits to the job. The president does not have the authority to make any policy he pleases.

We sometimes think it is the Supreme Court’s job to uphold those limits. But wise and successful presidents also learn to limit themselves. At the end of the day, the president is one of many public servants who will eventually resume private citizenship. Of modern presidents, Harry Truman understood this best of all. The president is not a Caesar. He is the chief executive officer of one branch of government, limited by custom, statute, and the Constitution of the United States of America.

First Published December 2, 2016, 5:00 a.m.