When President Obama announced his sweeping unilateral executive action on immigration last November, administration officials stressed that the new edict would not take effect immediately. One part of the president's action — changes to DACA, or Deferred Action for Childhood Arrivals, to extend the period in which illegal immigrants are protected from deportation to three years from its present two years, and also to extend work permits for the same time — was scheduled to go into effect Feb. 18, 2015, three months after the president's announcement. The other part of the president's action — the newly-created DAPA, or Deferred...