As we said at the time, “No doubt a lot of congressional investigations are partisan fishing expeditions. For better or worse, that comes with the democratic territory. Absent very strong countervailing considerations — stronger than some of those the administration has asserted in this case — Congress is generally entitled to disclosure.” Democrats, too, are entitled to disclosure, particularly as they ask weighty questions about the potentially severe abuse of power in the top reaches of the White House.

Mr. Trump’s own words reveal that he is motivated not by any specific concern about protecting presidential decision-making or some other crucial executive-branch function — but by concealing anything that might land him in political jeopardy. Courts have said little on the limits of executive privilege, but judges have been skeptical that the president has a generalized interest in secrecy that outweighs legitimate investigative inquiries. Given Mr. Trump himself admits that much of the information his aides might disclose has already been revealed in special counsel Robert S. Mueller III’s investigation, the president appears mostly interested in avoiding a public spectacle. That is not the purpose of executive privilege.