Read more: The Democrats’ missed opportunity on impeachment

But the Republicans’ legal expert brought a surprise, if one that received too little attention. Jonathan Turley submitted an extensive written statement, in which he disagreed with his fellow witnesses in myriad respects. But as he delivered his opening oral remarks, he cut to the heart of the matter: “The use of military aid for a quid pro quo to investigate one’s political opponent, if proven, can be an impeachable offense.”

It was easy to miss this line, especially as Turley quickly returned to railing against what he consistently characterized as an impeachment process moving too hastily. But this was it—the whole ball game.

This was the legal question to be answered at yesterday’s hearing. This is the legal question that every member of the House Judiciary Committee will have to answer when they vote on whether to refer out of committee articles of impeachment. And this is the legal question that every member of the whole House will have to answer when they vote on whether to send to the Senate articles of impeachment for a trial there.

Indeed, this is the legal question underpinning it all: Do the facts, as alleged, constitute an impeachable offense?

On this, there was unanimity among yesterday’s four witnesses. On this, there was a clear, single answer to emerge. And that answer was yes.

Turley’s opposition to Trump’s impeachment is, from his perspective, consistent with this surprising view. That’s because Turley said that a quid pro quo that trades public duty (military aid to an ally) for private gain (dirtying of a political rival) can be an impeachable offense “if proven.” And Turley made clear in later testimony that he does not believe it has been proved.

On this, Turley said: “I don’t see proof of a quid pro quo.” But Trump’s own chief of staff, Mick Mulvaney, publicly acknowledged this exact quid pro quo back in October. So did Trump’s ambassador to the European Union, Gordon Sondland, in sworn testimony before the House Intelligence Committee in November, at least with respect to the White House meeting. So Turley is just plain wrong here. Whether that reflects willful blindness or actual ignorance is of little moment.

But—and here’s the key point—Turley’s view of whether there was or wasn’t a quid pro quo is, itself, of no moment whatsoever. Unlike Sondland—indeed, unlike all those who testified before the Intelligence Committee in recent weeks—Turley was not called yesterday before the Judiciary Committee as a fact witness to testify about what actually transpired. He was called as a legal expert. He was called to articulate what the legal standard was, and whether, if the facts were established, that standard was met.

Read more: Writing articles of impeachment is exhausting

On that, Turley was clear, and Turley was right. He was the one witness House Republicans—fierce defenders, at least so far, of President Trump—called to explain to the American people what the Constitution means and, in particular, what the legal standards are for impeachment. They could have called anyone, and they called him.

That’s the end of any legal debate. It’s now simply a matter of reviewing the facts.

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