The Muslim ban could be up and running again in the US if the Trump administration is successful in its arguments to reinstate the executive order.
The case is expected to continue today, with an afternoon deadline for parties on both sides of the argument.
It comes after President Trump's appeal to have his executive order immediately reinstated was rejected.
He has since hit out at the judges behind the decision.
Just cannot believe a judge would put our country in such peril. If something happens blame him and court system. People pouring in. Bad!
— Donald J. Trump (@realDonaldTrump) February 5, 2017
I have instructed Homeland Security to check people coming into our country VERY CAREFULLY. The courts are making the job very difficult!
— Donald J. Trump (@realDonaldTrump) February 5, 2017
Kim Buckley has this report: