Treason. Traitor. These are some of the most serious accusations one can level, especially in politics. Yet it has now become commonplace to hear these terms bandied about against political adversaries. Those who President Donald Trump has branded as "traitors" include President Barack Obama, Robert Mueller's investigation, the New York Times, the mainstream media, former FBI director Andrew McCabe, and all Democrats.

"This transition is going to be quite ugly," says Carlton Larson, the Martin Luther King, Jr. Professor of Law at University of California, Davis. Larson is the author of a new book, On Treason. He discusses what treason is — and is not — and explains why there has only been one person indicted in America for treason. He also weighs in on whether Trump's actions in cozying up to foreign adversaries are treasonous.