Moreover, oversight of conflicts of interest is literally the entire reason this law came about in the first place. It was passed in 1924, in response to the Teapot Dome scandal and then-Treasury Secretary Andrew Mellon’s refusal to reveal his possible conflicts of interest.
That sort of thing is exactly why the American people deserve to see Trump’s tax returns. No president has ever continued to operate a vast business empire while in office. The conflicts of interests — plus instances of blatantly abusing his power to enrich himself — probably number in the hundreds. The man is plainly a crook.
So legally, it’s open-and-shut — indeed, as Harry Litman writes, “there is not a single case suggesting that the secretary has discretion not to comply with such a written request by the chairman of the Ways and Means Committee.”