...Whatever Trump Jr. did, it’s definitely not treason. Treason is a very specific crime with a definition set forth in the Constitution that Trump Jr’s conduct doesn’t come close to meeting, for one simple reason: The US is not at war with Russia.

Article 3, Section 3 of the Constitution lays out the definition of treason used in US criminal prosecutions: “Treason against the United States, shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort.”

I looked into this issue a few years ago when Edward Snowden faced accusations of treason for disclosing highly classified NSA surveillance programs. UC Davis law professor Carlton Larson told me then that there are two broad categories of treason charges: “aid and comfort” prosecutions, and “levying War” prosecutions.

The latter is rare, and typically involves someone who’s literally using an army to fight the government of the US or one of the 50 states. John Brown was convicted and hanged for treason against the commonwealth of Virginia in 1859 following his ill-fated attempt to launch a slave rebellion at Harpers Ferry. Former Vice President Aaron Burr was prosecuted unsuccessfully in 1807 on charges that he conspired to levy war against the United States and create an independent country in the center of North America, combining what are now some Western states with Mexican land.

Obviously, Trump Jr. did not actively conspire to wage a literal war with armies and troops and stuff against the United States. I mean, with the flood of damning leaks about the Trump administration occurring on a daily basis, I’m nervous about ruling anything out at this point, but it seems pretty unlikely.

“Aid and comfort” prosecutions are also difficult. The typical defendant is someone like American-born al-Qaeda member Adam Gadahn (the first treason indictment since World War II and its aftermath), or Nazi propagandist Robert Henry Best, or Tomoya Kawakita, a joint US-Japanese citizen who abused American prisoners of war who were forced to do labor at a mining plant he worked at in Japan.

What unites these cases is that they concern countries or organizations with which the US was at war, or at least a de facto state of war. The US is at war with al-Qaeda, as authorized by Congress, and the US had explicitly declared war against Germany and Japan in World War II. An “aid and comfort” prosecution requires that a defendant “adhere to” an enemy entity with which the US is presently at war.

And the US is not at war with Russia. Not even close. Indeed, when Julius and Ethel Rosenberg were prosecuted for sharing atomic secrets with the Soviet Union, they were not charged with treason. ...