Republicans look forward with some apprehension to President Obama’s threat to act unilaterally on immigration. Obama has already violated the clear letter of his own healthcare law in order to make it less painful to Americans during an election year, and he also tried to make two illegal executive appointments, only to be repudiated by a unanimous Supreme Court. There is little to suggest he will not follow through on this new threat.

Republicans will not find it easy to challenge his actions. It is often difficult to gain standing in court when an executive simply refuses to enforce the law. Impeachment would be an overreaction — and a politically damaging one for anyone who has bigger goals in mind, like seeing Obamacare repealed. And after last year’s drama, no one really wants another government shutdown.