But what happens if Trump disobeys court orders? Who becomes the referee when the referee itself is one of the combatants?

Short answer: Congress. Because Congress alone, through its impeachment power, has the constitutional authority to hold a president accountable for breaking the law.

A look at some of the pending court cases, and a bit of informed speculation about other cases likely to come, indicates Trump’s dilemma: He’ll have to choose between complying with a court order that could yield highly damaging information about him, or defying a court order that could itself create an article of impeachment for obstructing justice and failing to faithfully execute the laws.

In the last month alone, five courts have issued rulings against Trump. None of them had anything to do with the impeachment inquiry. Rather, four of them involved the border wall and immigration green card regulations. If Trump refuses to comply with those court orders, after all appeals have been exhausted, he could be creating new grounds for his own impeachment.