Donald Trump’s Senate impeachment proceedings is only a “trial” in a colloquial sense. Many Americans have some sense of how a case is tried in court, and this isn’t it.

Sen. Pat Leahy (D-Vt.), for example, is overseeing the proceedings, while also serving as a “juror.” He’s also, incidentally, a witness to the crime. In fact, in this case, each of the jurors are witnesses, which in a normal trial would never be permissible.

And because the usual rules and procedures of an American trial do not apply to the Senate’s impeachment proceedings, it stands to reason that there will be dramatic differences in how senators approach their responsibilities. But by any sensible measure, it’s tough to defend tactics like these.

[Republican Sens. Lindsey Graham, Mike Lee, and Ted Cruz] were seen going into a meeting with Trump’s lawyers after the trial wrapped for the day. “We were discussing their strategy for tomorrow and we were sharing our thoughts in terms of where the argument was and where it should go,” Cruz, who’s said he’ll vote to acquit the former president, told reporters afterwards. [Defense attorney David] Schoen said they discussed “procedure.”

Clearly, procedural considerations were not the sole focus. Not only did Cruz concede that the GOP senators offered ideas about what the defense attorneys should say, but members of Team Trump publicly thanked the Republicans for their recommendations.

Or put another way, using the loose terms applied to the impeachment process, this is a trial in which three jurors huddled in private with defense attorneys, offering guidance on how best to persuade other jurors.

There’s no reason to believe anyone involved will face any sanctions as a result of this, but don’t be too quick to dismiss the private chat as unimportant.

For one thing, David Schoen seems a little too eager to have it both ways. He’s repeatedly suggested, for example, that an impeachment trial should be seen as an actual trial — with due process in the House, literal criminal charges, etc. — only to turn around and have private, in-person communications with a trio of jurors.

For another, it’s no small matter that Graham, Lee, and Cruz apparently thought such a meeting was necessary. If Donald Trump’s acquittal were inevitable, and the House impeachment managers’ presentation changed nothing, why bother directing the former president’s defense attorneys?

But perhaps most important of all is the oath these Senate Republicans swore to uphold.

Article 1, Section 3 of the Constitution reads, “The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation.” And what does that oath entail? I’m glad you asked.

The Senate rules on impeachment trials require members to take this oath: “I solemnly swear (or affirm) that in all things appertaining to the trial of ____, now pending, I will do impartial justice according to the Constitution and laws, so help me God.”

Graham, Lee, and Cruz aren’t just ignoring this vow, they’re flaunting their indifference to their responsibilities.