Treason is the crime of betraying one's country. Sounds simple. But is it?

In a speech Monday, President Donald Trump agreed with the suggestion that Democratic congressmen committed treason for failing to applaud key parts of his State of the Union address last week. 

A White House spokesman says he was "joking." But even conservative commentators like Bill Kristol have said Trump's use of the term is "a disgrace."

Treason is no joke. “It’s the worst crime known to the law,” says Carlton Larson, a professor of law at the University of California at Davis.

“I don’t think that Trump meant it in that serious a sense,” says Larson. “I think it was a sort of a throwaway comment. But it’s still an unhelpful and particularly nasty throwaway comment because you’re using it to accuse your political enemies” of such an egregious crime.

“Treason is different in each country of the world,” explains Larson. “But in the United States it’s defined explicitly in our Constitution as either levying war against the United States or adhering to their enemies, giving them aid and comfort.”

Larson says the framers of the Constitution thought long and hard about treason and deliberately used a narrow definition.

“It’s very easy for people to confuse disagreement with the government with outright treason and disloyalty,” says Larson. “And that’s been a problem throughout human history. How do you get a so-called ‘loyal opposition?’ To what extent can you have people who are bitterly opposed to the government but at the same time are not actually traitors?”

Prosecutions for treason are rare, and no one has ever been executed for treason against the United States since the Constitution was written. That isn’t to say treason hasn’t been committed. “The Civil War, for example, was a significant act of treason,” says Larson, “with people levying war against the United States. But no person was ever executed for that.”

An attempt to prosecute Jefferson Davis, the president of the Confederacy, for treason, ultimately failed.  

Scientists Julius and Ethel Rosenberg are often mistakenly believed to have been executed for treason after passing nuclear secrets to the Soviet Union during the Cold War. However, the actual charge for which they went to the electric chair was conspiracy to commit espionage. The United States was not at war with the Soviet Union “and therefore,” says Larson, “a treason charge couldn’t legally be brought against the Rosenbergs.”

Some of Trump’s political enemies have used the term ‘treason’ in connection with the Trump campaign’s ties to Russia. “But you have the same problem as with the Rosenbergs,” says Larson. “That Russia is not technically an enemy. We are not at war with Russia.”  So even if their actions were harmful to the United States, “that alone doesn’t make for a case of treason,” says Larson. 

From PRI's The World ©2017 PRI