Usurp is exactly the right word, Gary. When the Constitution gives specific authority over immigration to the Congress, and Congress writes specific laws delegating that authority to the President, and multiple presidents have exercised that very power without judicial interference until now, the Judicial branch is usurping that power by asserting their right of review and nullification of the President's action until such time as they slow-walk their way through that review. Mr. Trump's action was not overreach, but the court's action certainly was. This is likely to continue throughout Mr. Trump's presidency, as the Democrats have no power available to them except for this, and they don't like it. So when the duly elected President and Congress are thwarted by the Judiciary which is supposed to uphold existing law, not question it with out end, "usurp" is exactly the right word. Think more clearly about the Constitutional role of each branch, rather than about a specific outcome.