The best we can hope for at this point on the Supreme Court and Trump's taxes is that Trump is defeated in November, because oral arguments in the cases went so badly for House Democrats it was comical. The reality is that Trump should lose both cases 9-0, as Vox's Ian Millhiser points out.
It’s tough to exaggerate just how thoroughly current Supreme Court precedents cut against Trump. The Court has repeatedly emphasized that Congress must have a broad power to conduct investigations, because it is not possible for Congress to make informed law-making decisions without such investigations.
As the Supreme Court explained in Eastland v. United States Servicemen’s Fund (1975), “the power to investigate and to do so through compulsory process ... is inherent in the power to make laws.” Without such a power, “a legislative body cannot legislate wisely or effectively in the absence of information respecting the conditions which the legislation is intended to affect or change.”
Eastland is one of many Supreme Court decisions emphasizing that Congress may conduct nearly any investigation, so long as that investigation is “intended to gather information about a subject on which legislation may be had.”
Courts, moreover, are forbidden to dig into the legislature’s reasons for conducting a particular investigation. “So long as Congress acts in pursuance of its constitutional power,” the Court held in Barenblatt v. United States (1959), “the Judiciary lacks authority to intervene on the basis of the motives which spurred the exercise of that power.”
So that’s what the law says. And under that law, the House wins both Mazars and Deutsche Bank. The first case involves a House Oversight Committee investigation targeting the president’s accounting firm, Mazars USA. It seeks information on whether existing presidential financial disclosure laws are sufficiently robust, or whether they need to be stricter.
Similarly, the Deutsche Bank case involves two parallel House investigations targeting banks that possess some of Trump’s financial records. Among other things, those investigations seek information on whether there are “any links and/or coordination between the Russian government, or related foreign actors, and individuals associated with Donald Trump’s campaign, transition, administration, or business interests, in furtherance of the Russian government’s interests.” These investigations could inform legislation seeking to reduce foreign money laundering and to reduce foreign interference in US elections.
But the court, or at least five justices on it, are purely political creatures now.
Not long after Letter began his argument, Chief Justice Roberts revealed just how sympathetic he is to Trump’s position. Letter’s brief, Roberts noted, states that a congressional investigation must “concern a subject on which legislation can be had.” According to Roberts, this “test is really not much of a test” because it doesn’t impose significant limits on congressional investigations of the president.
Roberts isn’t wrong that the test laid out in Letter’s brief is very permissive of congressional investigations. But it’s not like Letter just made that test up. The idea that Congress may conduct any investigation that concerns “a subject on which legislation can be had” was endorsed by many prior Supreme Court decisions over the course of many decades.
Roberts’s disdain for this longstanding standard was echoed by several of his colleagues. Justice Neil Gorsuch dismissed it as “limitless.” Justice Brett Kavanaugh worried that it would permit congress to declare “open season” on presidents. And Letter was unable to offer a new limit on congressional investigations that would satisfy these justices.
Meanwhile, Justice Samuel Alito repeatedly accused the House of issuing these subpoenas to harass the president — a fact that is irrelevant under Barenblatt’s holding that “the Judiciary lacks authority to intervene on the basis of the motives which spurred the exercise of that power.”
Even Justice Stephen Breyer, a Clinton appointee, appeared to lose confidence in Letter’s arguments. Shortly before those torturous arguments came to an end, Breyer said that he’s concerned that the House is seeking “a lot of information and some of it is pretty vague,” and that the task of sorting through these requests and figuring out what information is being turned over could prove too much of a distraction.
It would be hard to sugarcoat this: It was a disaster for Letter and the House. Letter began his argument with a wealth of precedents that clearly support his client’s position, and he appeared completely unprepared for a Court that just does not believe that existing law should apply to President Trump.
So yes, absolute best case scenario here is that Roberts punts this back to the lower courts to examine the question of if an Congressional investigation is just too hard for the Executive to put up with unless Congress can specify before the investigation what it should have found, or some other time travel/psychic nonsense, after the election.
By then it'll either be moot because of a President Biden, or moot because we won't have a democracy.