In refusing to turn over Mr. Trump’s tax returns and in suits seeking to stop private businesses from providing records concerning the president’s business activities, Steven Mnuchin, the Treasury secretary, and Mr. Trump’s lawyers have said there was no “legitimate legislative purpose” for the requests, notwithstanding a federal law concerning the returns and questions about whether Mr. Trump has violated constitutional restrictions on doing business with foreign entities.
Raymond W. Smock, who served as historian of the House from 1983 to 1995, said it was one thing for Mr. Trump to assert a privilege and another for him to presume to decide what was a legitimate legislative purpose. “That is part of the arrogance the Trump administration is exhibiting all up and down the line,” Mr. Smock said.
In a 1927 decision arising from the Teapot Dome scandal, concerning government corruption, the Supreme Court said that congressional inquiries were “an essential and appropriate auxiliary to the legislative function.” To enact sensible laws, and to carry out their other responsibilities, the Supreme Court said, lawmakers must have access to information.
Congress’s power to punish refusals to cooperate is a more complicated matter. In theory, it can take matters into its own hands, instructing the sergeant-at-arms to take witnesses into custody until they agree to testify. That method has not been used since 1935.
It could ask the Justice Department to pursue contempt proceedings, but earlier administrations have refused to cooperate in disputes involving executive branch officials, and the current one would no doubt follow suit.
The House can go to court on its own, and probably will, but the resulting proceedings are likely to be lengthy. If history is a reliable guide, the administration is likely to lose confrontations over congressional subpoenas, though is not clear that the Trump administration would comply with any eventual court order.
There is a fourth alternative, one that serves two goals, said Michael Conway, who served as counsel to the House Judiciary Committee during impeachment proceedings against President Richard M. Nixon. Were the House to open impeachment proceedings against Mr. Trump, its right to gather information would be strengthened, Mr. Conway said. And refusal to cooperate with such inquiries, he added, could itself be an impeachable offense.