The Trump administration must comply with congress's impeachment inquiry. It is constitutionally mandated, and is a core tenet of the principal of separation of powers. Since the president, by the DOJ's Office of Legal Council has said that a sitting president should not be indicted, the impeachment process is the only way to hold the president accountable for wrongdoing. If the president can ignore the process and refuse to cooperate, it undermines our democracy. He MUST comply.