Legal analysis

In a new book by Michael Wolff, "Fire and Fury: Inside the Trump White House," former White House chief strategist Steve Bannon calls a meeting between Trump campaign officials and a Russian lawyer during the presidential campaign "treasonous" and "unpatriotic."

The meeting at Trump Tower may or may not have been unpatriotic.

But it was not treason.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Treason is a unique crime. The U.S. Constitution mentions only three federal crimes: counterfeiting; piracy and felonies committed on the high seas; and treason. It provides a limiting definition of only one: treason.

The Treason Clause of Article III states: "Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No Person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in Open Court." It also establishes a strict burden of proof of two witnesses for a conviction. The modern treason statute is 18 U.S.C. § 2381; it tracks the language of the Constitution.

According to Carlton Larson, a constitutional scholar and law professor at the University of California, Davis, the framers had a reason for singling out, and narrowly defining, treason: They did not want this serious crime used as a political weapon against political adversaries.

The Trump Tower meeting could not be an act of treason because Russia is not and was not an "enemy" of America at the time of the meeting. The term "enemies," as used in the Treason Clause, applies only to a foreign power in a state of open hostility with the U.S., i.e., war. Russia might be an adversary to the U.S. It might be a competitor. For purposes of the Treason Clause, however, Russia is no more an "enemy" to America than Australia or the U.K.

Related: Will Trump be charged with collusion?

Even if the Trump team had communicated with an "enemy" of the United States — which it did not — more than a conversation would be required to establish the "aid and comfort" required under the Treason Clause, like money, or shipments of TOW missiles.

Dozens of other crimes could potentially apply to charges of collusion with Russia, including espionage, campaign/election laws, and anti-hacking laws. Just not treason. Bannon's use of the word "treasonous" could be construed as an accusation of a crime — one that is legally impossible here.

It's probably not even defamatory, though, for Bannon to call the Trump Tower meeting "treasonous."

The Supreme Court found in 1974 that a union publication accusing a scab worker of being a "traitor," and even identifying people with a list of names, could not reasonably be understood to accuse the individuals of the crime of treason. The Court reasoned that loose language and undefined slogans are part of the conventional give-and-take of political controversies. They are not a falsification of facts.

Bannon's opinion that the Trump team's conduct was "treasonous," even in the most pejorative terms, is likely protected speech.

Danny Cevallos is an MSNBC legal analyst. Follow @CevallosLaw on Twitter.