Not optional
Did McGahn surprise us all and heed the subpoena? Nah.
“Our subpoenas are not optional,” Mr Nadler said during his opening remarks on Tuesday. “This committee will hear Mr McGahn’s testimony even if we have to go to court.”
Mr McGahn could be held in contempt for defying the subpoena from Congress.
“We will not allow the president to block congressional subpoenas, putting himself and his allies above the law,” Mr Nadler added.
…
Both the Department of Justice and White House released statements on Monday arguing that Mr McGahn was under no obligation to give evidence.
You might as well say “the Five Families released statements on Monday arguing that Mr McGahn was under no obligation to give evidence.” It’s every bit as meaningful. Trump’s grotesquely compliant employees released statements on Monday arguing that Mr McGahn was under no obligation to give evidence; of course they did; they’re all in for their mob boss.
And what mechanism do we have to enforce the subpoena (genuine question; I don’t know)? It’s looking like, yet again, we don’t actually have the rule of law because the only thing required to break it is just to declare that you will, and no consequences follow.
From what I can gather they can declare him in contempt, and they could send federal marshals to drag him in. And/or they can start the impeachment process which would rule out White House obstruction. I forget and/or don’t understand the details, but they have added powers in an impeachment process. Some Dems are saying that’s why we have to do it now, so that we can get the Mueller report and haul in the witnesses.
Put impeachment aside for the moment; it’s technically a different issue, because while being in contempt of Congress is a possible grounds for impeachment, it’s not really a remedy for contempt.
Wiki has a good summary, and this Atlantic article explores the boundaries a bit.
In a nutshell:
1) The power Ophelia refers to @2 of having someone arrested is called “inherent contempt.” It hasn’t been used since 1934, but that doesn’t mean it’s gone away. But I think it’s unlikely to be used here, because it’s quite drastic and risks setting off a violent confrontation: if the Sergeant-At-Arms shows up to arrest Bill Barr or some other federal official, and the official’s personal security detail refuses to permit it, what then?
2) The option used since 1934 involves a reference to the courts, with either the Department of Justice prosecuting based on Congress’s request, or Congress bringing suit itself if DOJ refuses. That has the problem of being slower, but it probably has more legitimacy in the public’s eyes because a third branch of gov’t is getting involved.
3) The Atlantic article speculates on some other remedies, such as fines, but as they haven’t been tried yet, it’s hard to see how that doesn’t just end you up in federal court on a much dodgier case (because Congress is relying on a heretofore-untested theory) than if Congress just sued in court to enforce the contempt.