But he lost both decisions in terms of the legal issues. This shouldn't be surprising, of course, since his legal position is so many light years beyond the pale of US constitutional norms. As the Supreme Court rightly put it, he is in effect claiming to be a King, despite two centuries of legal and political history to the contrary.
Given the egregiousness of his likely crimes and the already compelling evidence of them, it seems clear that the House of Representatives should be able to make a case for extensive discovery that no reasonable court, acting in good faith, could credibly rebut. (Which is not to say that no judges or justices will try.) But the time frame for this is long enough that it might not matter. If he stays in the White House post-election, it is not clear to what extent normal legal norms will matter. If he is out, this might be the least of his problems.
One odd feature of Trump v. Mazars that caught my attention is the following passage, which I have taken from the up-front syllabus of the decision:
"Historically, disputes over congressional demands for presidential documents have been resolved by the political branches through negotiation and compromise without involving this Court. The Court recognizes that this dispute is the first of its kind to reach the Court; that such disputes can raise important issues concerning relations between the branches; that similar disputes recur on a regular basis, including in the context of deeply partisan controversy; and that Congress and the Executive have nonetheless managed for over two centuries to resolve these disputes among themselves without Su- preme Court guidance. Such longstanding practice ' ‘is a consideration of great weight’ ' in cases concerning 'the allocation of power between [the] two elected branches of Government,' and it imposes on the Court a duty of care to ensure that it does not needlessly disturb 'the compromises and working arrangements' reached by those branches.'"
This is an extraordinarily, perhaps even willfully, blind thing to say when you have an administration that has, as its position, allowing no Congressional discovery whatsoever. In context, the rogue nature of the current administration is something that should be judicially cognizable. You can't reasonably defer to the political branches working things out when one of them has decided to act in bad faith and without regard to the Constitution, the principle of separation of powers, or 200 years of previously undisputed practice. The current administration makes no secret of, and leaves no possible ground for doubt concerning, its wholesale rejection of "compromises and working arrangements" that reflect the existence of coequal executive and legislative branches.