Washington CNN  — 

Almost exactly a year ago, on the eve of Thanksgiving, Chief Justice John Roberts issued a stunning rebuke to President Donald Trump. As many people were heading out of town for the holiday, Roberts called out the President.

“We do not have Obama judges or Trump judges, Bush judges or Clinton judges,” Roberts said in a statement responding to comments Trump had made criticizing an appellate court. “What we have is an extraordinary group of dedicated judges doing their level best to do equal right to those appearing before them. That independent judiciary is something we should all be thankful for.”

Criticism, with much stronger rhetoric, often ricochets between the political branches, but a statement such as that from a chief justice directed at the President was rare.

In the end, it made little difference, as the President took to Twitter to criticize the Chief, and Roberts thereafter kept his fire dry.

But a year later, as the country prepares again to celebrate Thanksgiving, the relationship between the two men is once again center stage, and this time the President could use Roberts’s vote. The two men, both heads of their respective branches, could once again be poised to clash and the result could have lasting impact on the relationship between the branches of government.

Trump has hired private lawyers to fight a subpoena to his long time accounting firm in a bid to shield his financial documents and tax returns. He has lost in the lower courts, and now the issue is before the Supreme Court. The cases don’t concern the government’s Travel Ban or its decision to terminate DACA or to add a citizenship question to the census. For Trump, it’s about an intrusive subpoena for his personal records.

Additionally, in the coming weeks, Roberts, already grappling with a momentous term and the fragile health of the leading liberal on the bench, may be called upon to cross the street and preside over Trump’s potential impeachment trial.

As early as Monday the Court could rule on one of the cases concerning Trump’s request to block a House subpoena to Mazars USA, his accounting firm. Lower courts rejected the President’s broad claims that the subpoena violates the separation of powers, holding instead, that the House was well within its authority to pursue the documents as part of its legitimate legislative function. But Trump’s personal lawyers are asking the justices to put the lower court ruling on hold for now, so they can appeal it.

Tax returns

Coupled with another case concerning a New York grand jury subpoena, Trump’s lawyers are making broad arguments concerning the separation of powers and absolute immunity. How the court handles the cases could impact several other similar cases currently playing out in the lower courts, and potentially even touch on issues that could come up in the impeachment proceedings.

The justices could step in and make a broad statement about Congress’ investigatory powers and his argument that he is immune from criminal proceedings while in office.

If the Court denies the President’s emergency request to put the subpoena on temporary hold, the House will finally get the documents and the justices will have shown little deference to a sitting President.

If the justices grant the President’s request, it would represent a win for Trump for now and the court’s move could tee up a potentially landmark separation of powers case that would likely be heard this term. The move would also delay, for at least several weeks, the House’s ability to obtain information it says is critical to Congress’ power to conduct oversight. Although the case predates the impeachment proceedings, the order would be a setback for House Democrats and the President’s critics.

It would take five justices to grant such an emergency request, and Roberts, working behind the scenes, is likely grappling with how to respond. His vote has the same weight of his colleagues, but he will take into consideration the court’s institutional concerns more than any other justice.

While the justices deliberate, Trump will be in a holding pattern waiting for the Court – including two of his nominees – to rule. The House has already indicated that if the justices block the documents for now, the court should agree to hear the appeal this term.

Impeachment trial?

Meanwhile, in the coming weeks, Roberts is also likely to be called upon to serve as the presiding officer in a potential impeachment trial in the Senate chamber.

“When the President of the United States is tried, the Chief Justice shall preside,” the Constitution says.

That would mean that while his court is in the middle of a momentous term including cases on LGBT rights, abortion, and the Second Amendment. Roberts will also don his black robe and serve as the presiding officer for an impeachment trial.

Roberts, who has worked to keep the court out of the political fray, would find himself in the middle of it all. Senate impeachment rules revised in 1986 hold that the Presiding Officer on the trial shall direct “all the forms of proceedings while the Senate is sitting” and “may rule on all questions of evidence” but also includes a provision where the Chief could, instead, “submit any such question to a vote of the members of the Senate.”

And once again, the President, who has launched unprecedented attacks on the judiciary, will wait for the rulings.