Immigration authorities have rounded up nearly 200 Iraqis in recent weeks, and the Trump administration is now under heavy pressure to hold off moves to deport them.
Many of those currently detained are from the minority Chaldean Christian community, which faces severe persecution in Iraq.
U.S. immigration authorities say the detained Iraqis have criminal records, but their families and supporters say many have already served time or paid their fines and that they would face persecution if sent back.
A lawsuit on behalf of the Chaldean Christians was heard in court Wednesday in Detroit. The American Civil Liberties Union is seeking a temporary stay of the deportations.
Protesters outside the Detroit courtroom Wednesday shouted in support of the detained Iraqis, Michigan Radio reports. Some held signs depicting President Trump that read "You Vowed To Protect Us."
On the campaign trail and in office, Trump has vowed to help persecuted Christians in the Middle East.
The ACLU lawsuit includes the stories of seven lead plaintiffs, including several who came from Iraq as refugees and have been in the U.S. for 20 years or more.
Russell Moore of the Southern Baptist Convention says many evangelical Christians and Catholics are "deeply concerned about the possible return of Chaldean Christians to the Middle East, knowing this would essentially be a death sentence."
Moore is one of many Christian leaders pleading with the Trump Administration not to deport the Chaldean refugees.
If a judge does not step in, the detainees could be deported as soon as next week.