The best legal arguments against Trump's immigration ban

Is President Trump’s recent executive order on immigrants and refugees legal?

It’s a surprisingly tricky question.

The order arguably violates both a federal statute and one or more sections of the Constitution – depending on whether the immigrant is already in the U.S. In the end, opponents’ best hope for undoing the order might rest on the separation of church and state.

Trump’s order bars the entry of any refugee for 120 days, and Syrian refugees indefinitely. It also bans citizens of Iraq, Iran, Syria, Somalia, Sudan, Libya and Yemen from entering the U.S. for 90 days. This order potentially