Here's what you need to know before Monday's arguments:
What to expect on Monday
Lawyers will argue their case en banc — before a panel of all active and eligible judges of the 4th Circuit Court of Appeals, which covers Maryland, North Carolina, South Carolina, Virginia and West Virginia. Each side gets half an hour to argue its case, and the judges may extend that time for questioning.
There are 15 active judges on the 4th Circuit, and it will be announced early Monday morning whether any of the 15 will recuse themselves.
According to the 4th Circuit's clerk, it's very rare that an initial hearing is heard en banc in the circuit. Typically, cases are first heard by a three-judge panel. An en banc hearing is granted only when a majority of active judges determine that the proceedings involve a question of exceptional importance or when uniformity of the court's decisions is needed.
It is highly unlikely that the judges will issue a ruling on Monday. A decision could come in the next few weeks.
What happens afterward?
Monday will the first time that a case on the revised travel ban is heard before an appeals court. The government is appealing U.S. District Judge Theodore Chuang's March 15 ruling in Maryland that granted a nationwide preliminary injunction on one part of the revised travel ban, section 2(c), which bars entry of nationals who aren't U.S. permanent residents from six Muslim-majority countries for 90 days. Chuang did not block any other part of the executive order.
A different group of plaintiffs will face off against the government before a three-judge panel in the 9th Circuit on May 15. In that case, the government is appealing a ruling by Hawaii District Court Judge Derrick Watson that imposes a nationwide preliminary injunction on two provisions of the executive order: the ban against nationals from six Muslim-majority countries for 90 days and the 120-day refugee ban. Whichever side loses before the 9th Circuit's three-judge panel may ask for a rehearing en banc, before all active 9th Circuit judges, or the judges may vote for a rehearing. The parties could choose to skip that step and appeal to the U.S. Supreme Court.
If one of the circuit courts rules for the government before the other has decided, the travel ban will remain blocked because a circuit court does not supersede a district court in a different jurisdiction.
Conflicting district court decisions could lead to the case's moving to the U.S. Supreme Court more quickly.
There are additional cases on the executive order pending throughout the country; these two cases are the first to be heard on appeal.