President Obama is facing the very real possibility of a deadlock at the Supreme Court that guarantees his immigration actions won’t take effect before he leaves office. If the justices split 4-4 on the case, as observers say is possible, the president’s attempt to shield nearly 5 million people from deportation would be sent back to the lower courts for another lengthy legal battle that would surely spill into the next administration. Oral arguments in the case are set for April 18, which means a decision could come in late June. The high court has already deadlocked twice since the...