The ruling will mainly effect illegal immigrants who unlawfully migrated but bore children on US soil, thus making them rightful citizens; legitimizing Obama's plan would grant the parents of these children numerous amenities.

"They are looking into whether the president cannot enforce a law, because essentially that's what he's doing", Roldan said. At issue is a plan focusing on almost 4.5 million illegal immigrants who are parents of American citizens or lawful permanent residents. "We applaud the Supreme Court for taking on this case, and we are confident they will rule in favor of hardworking immigration families and the administration's commonsense executive actions".

Those eligible for Obama's program, directed at undocumented immigrants with no criminal record, would be able to work legally and receive some federal benefits. In November, a divided three-judge panel upheld an injunction issued by a U.S. District Court in Brownsville, Texas, shutting down the program while the legal case, United States v. Texas, proceeds. "This is what we have been pushing for", Thanu Yakupitiyage said. However, Roldan said the justices will look into more than President Obama's authority to enact that immigration policy.

Nationwide, the number of undocumented immigrants has declined in recent years because of the state of the USA economy, stepped-up enforcement of border security and workplace immigration laws.

The State of Texas, acting on behalf of 26 states, challenged the program's constitutionality and has won every legal challenge so far, the Associated Press reports. Amparo came to the U.S.as an undocumented immigrant from Mexico.

The executive actions build on 2012's Deferred Action for Childhood Arrivals (DACA), which granted relief to young adults who came to the U.S.as children.

In order to have such standing, a state has to show that it would be injured in a concrete way if the president's action were to be carried out. Indeed, the justices broadened the scope of the case, asking the two sides to address an additional, and fundamental question: whether the president's action violates the Constitution's requirement that the president "shall take care that the laws be faithfully executed".

As per the usual for blockbuster cases, Pelley mentioned that the Court will decide by late June "whether the President overstepped his power".

Working against the president is deep uncertainty about what happens to those who apply for protection if a Republican who opposes Obama's actions wins the White House.

The programs were announced more than a year ago.

Arizona Attorney General Mark Brnovich said, "we hope that the Supreme Court takes this opportunity to decide whether the President exceeded his constitutional authority by bypassing Congress, and unilaterally rewriting our immigration laws". Republican candidates Ted Cruz and Marco Rubio said as president they would undo Obama's immigration moves.