As cheers and chants from immigration supporters and opponents filled the air outside the U.S. Supreme Court on Monday, the justices struggled over the legality of Obama administration’s plan to delay temporarily the deportation of nearly 4 million illegal immigrants.

At the end of the 90-minute argument, the eight justices appeared divided on the threshold question of whether Texas had standing to challenge the immigration plan in federal court and divided over the fundamental issue of whether the plan violates federal law and the Constitution.