WASHINGTON (AP) - The Supreme Court has upheld President Donald Trump's ban on travel from several mostly Muslim countries, rejecting a challenge that it discriminated against Muslims or exceeded his authority.

The 5-4 decision Tuesday is the court's first substantive ruling on a Trump administration policy. Chief Justice John Roberts wrote the majority opinion, joined by his four conservative colleagues.

Roberts wrote that presidents have substantial power to regulate immigration. The court may have signaled its eventual approval in December, when the justices allowed the policy to take full effect even as the court fight continued and lower courts had ruled it out of bounds.

WATCH: Full @ABC News Special Report: Supreme Court upholds President Trump's travel ban in 5-4 decision. https://t.co/4MscMOWmbP pic.twitter.com/Wij0SBUB1u

— ABC News (@ABC) June 26, 2018

Louisiana Attorney General Jeff Landry issued the following statement.

 “The Supreme Court just ruled that the President lawfully exercised the broad discretion granted to him under Section 1182(f) to suspend the entry of aliens into the United States. I applaud the majority for defending the Constitution and upholding the rule of law. In February, I joined state leaders from across the country in a legal brief supporting the President’s Proclamation; today, our request was granted. Today is a victory for America and her citizens.”