Legal battles are playing out across the U.S. as opponents of President Donald Trump's travel ban on citizens from seven predominantly Muslim nations take their fight to the courtroom. Hearings were being held Friday in a few of the cases.

A look at some of the court challenges:

MASSACHUSETTS

A federal judge in Boston is hearing arguments Friday on a request to extend a temporary injunction against the travel restrictions.

A seven-day stoppage was granted Sunday in a lawsuit filed by the American Civil Liberties Union on behalf of two state university professors who were detained at Boston's airport as they returned home from an academic conference. Both are Muslims from Iran and lawful permanent U.S. residents.

WASHINGTON

A federal judge will hear arguments Friday from Washington state for a temporary restraining order that would bar enforcement of portions of the ban. The state attorney general filed a lawsuit on Monday arguing the order is unconstitutional. The state says the restraining order is needed to protect residents and businesses from suffering irreparable harm.

VIRGINIA

Also Friday, a judge in Alexandria will hear arguments on a lawsuit challenging aspects of Trump's ban.

Virginia Attorney General Mark Herring, a Democrat, is seeking to join the lawsuit and broaden its scope. When it was first filed, it focused primarily on green-card holders who were affected by the ban. Herring's motion indicates he would seek protections for those on student and work visas and those with refugee status as well.

NEW YORK

A Brooklyn judge on Thursday extended a temporary restraining order to Feb. 21, but the Justice Department said it will ask her to throw out the case.

U.S. District Judge Carol Amon's ruling extended a stay that had been issued Saturday by a different judge and would have expired Feb. 11. Amon extended the order to give more time the government and civil liberties organizations to file paperwork.

MICHIGAN

A federal judge in Detroit says U.S. green-card holders shouldn't be affected by the order.

The Arab-American Civil Rights League argued in a suit filed this week in Detroit's U.S. District Court that the executive action is unconstitutional and targets immigrant communities.

A restraining order released Friday from U.S. District Judge Victoria Roberts covers legal permanent residents, not some others that also are part of the lawsuit. She says lawyers for the government clarified to her that the ban doesn't apply to "lawful" permanent residents.