Opponents of President Donald Trump's ban on travelers from several mostly Muslim countries are demonstrating outside the Supreme Court .

Demonstrators that gathered outside of the courthouse Wednesday morning as rain fell held signs that read "No Muslim Ban. Ever." and "Refugees Welcome" among other things. Demonstrators also displayed large mock-ups of passports from countries affected by the ban.

The Supreme Court is saving one of its biggest cases for last. The justices are hearing arguments Wednesday over President Donald Trump's ban on travelers from several mostly Muslim countries.

It's the last case the justices will hear until October.

The Trump administration is asking the court to reverse lower court rulings striking down the ban. The policy has been fully in effect since December, but this is the first time the justices are considering whether it violates immigration law or the Constitution.

The court will consider whether the president can indefinitely keep people out of the country based on nationality. It will also look at whether the policy is aimed at excluding Muslims from the United States.

People have been waiting in line for a seat for days.

The current version of the ban applies to travelers from five countries with overwhelmingly Muslim populations — Iran, Libya, Somalia, Syria and Yemen. It also affects two non-Muslim countries, blocking travelers from North Korea and some Venezuelan government officials and their families.