Donald Trump is shrugging off the Supreme Court. These are uncharted waters.

President Donald Trump shakes the hand of Supreme Court Justice Amy Coney Barrett as others on the court look on. He's now setting up a potential showdown.

AP Photo/J. Scott Applewhite

• The Supreme Court told Donald Trump to bring back a man his administration has deported to a prison in El Salvador.
• It doesn't look like Trump is going to comply — or even try to comply.
• Checks and balances among wings of government are built into the US system. What happens if that breaks down?