Legal battle over travel ban pits Trump's powers against his own words

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The 9th U.S. Circuit Court of Appeals in San Francisco is expected to rule only on the narrow question of whether a lower court's emergency halt to an executive order by Trump was justified. Trump signed the order on Jan. 27 barring citizens from seven Muslim-majority countries for 90 days and halted all refugee entries for four months.

The James R. Browning U.S. Court of Appeals Building, home of the 9th U.S. Circuit Court of Appeals, is pictured in San Francisco, California February 7, 2017. REUTERS/Noah Berger

The appeals court has several options. It could kick the case back to lower court judge James Robart in Seattle, saying it is premature for them to make a ruling before he has had a chance to consider all the evidence. Robart stopped Trump's order just a week after he issued it and before all the arguments had been developed on both sides.

Or the panel of three appellate judges could side with the government and find halting the order was harmful to national security, reinstating it while the case continues.

Their decision is "one step in what will be a long, historic case," Stephen Yale-Loehr, a professor at Cornell University Law School who specializes in immigration. Ultimately, the case is likely to end up in the U.S. Supreme Court, legal experts said.

The case is the first serious test of executive authority since Trump became president on Jan. 20, and legal experts said there were three main issues at play for the judiciary.

The broad questions in the case are whether the states have the right to challenge federal immigration laws, how much power the court has to question the president's national security decisions, and if the order discriminates against Muslims.

Washington state filed the original lawsuit, claiming it was hurt by the ban when students and faculty from state-run universities and corporate employees were stranded overseas.

Trump administration lawyer August Flentje argued at an appeals court hearing on Tuesday that the states lack "standing" to sue the federal government over immigration law, but his arguments were questioned by the judges.