Trump's travel ban faces U.S Supreme Court showdown

President Donald Trump

The first big showdown at the US Supreme Court over President Donald Trump's immigration policies is set for Wednesday, when the justices hear a challenge to the lawfulness of his travel ban targeting people from several Muslim-majority countries.

The case represents a test of the limits of presidential power. Trump's policy, announced in September, blocks entry into the United States of most people from Iran, Libya, Somalia, Syria and Yemen. Chad was previously on the list but Trump lifted those restrictions on April 10.

The high court has never decided the legal merits of the travel ban or any other major Trump immigration policy, including his move to rescind protections for young immigrants sometimes called Dreamers brought into the United States illegally as children.

It has previously acted on Trump's requests to undo lower court orders blocking those two policies, siding with him on the travel ban and opposing him on the Dreamers.

Trump's immigration policies - also including actions taken against states and cities that protect illegal immigrants, intensified deportation efforts and limits on legal immigration - have been among his most contentious.