The U.S. Conference of Catholic Bishops on Tuesday asked the Supreme Court to uphold the Obama administration’s temporary relief for millions of undocumented persons in the U.S. eligible for deportation.

“Courts have repeatedly recognized that there is a public interest in maintaining stable families and communities,” stated an amicus brief filed March 8 by the USCCB and other faith-based groups.

At stake in United States v. Texas is Obama’s 2014 executive action, the Deferred Action for Parents of Americans and Lawful Permanent Residents, that delayed the deportation of millions.

The action granted parents with children born in the U.S., and thus citizens or lawful permanent residents by birthright, a stay on their deportation if they met certain conditions like having lived in the U.S. for at least five years, passing a background check, and paying taxes. Up to 3.7 million persons could be eligible, the Migration Policy Institute estimated, as cited in the brief.

Certain persons were prioritized for deportation, including felons, terror suspects, and some gang members.

Combined with its expansion of the previous executive order, the Deferred Action for Childhood Arrivals which applied to children of parents who illegally entered the U.S., up to 5.2 million could benefit from the whole policy.

Twenty-six states filed for an injunction on having to implement the program. A Texas district court judge in 2015 ruled that the state did not have to do so, and the Fifth Circuit upheld the injunction.

If the federal government loses at the court, it could mean that millions of persons in the U.S. are at risk of deportation. The action is “a measure of mercy,” the brief argued, “providing peace of mind to nearly nine million people, including 4.5 million children.”

The USCCB was joined by other Christian groups such as the General Assembly of the Presbyterian Church (U.S.A.), the Leadership Conference of Women Religious, the Franciscan Action Network, the Mennonite Central Committee U.S., the National Latino Evangelical Coalition, and the National Hispanic Christian Leadership Conference.

These groups work first-hand with immigrants, the brief claimed, so they “have unique and firsthand knowledge of the adverse impacts that family separation, immigration detention and deportation have on immigrant families in the U.S., particularly young children.”

The Secretary of Homeland Security has the legal authority to grant a stay of deportations under the Administrative Procedure Act, the brief argued, because splitting up families through deportation would harm both those families and the public interest.

“Family unification is an integral consideration in the application of immigration law,” amici stated.

Children can suffer “emotional and social harm” resulting from the deportation and even detention of their parents, the brief claimed. Families who lose the breadwinner can suffer from losing income and thus being unable to pay household bills or properly feed themselves. In “extreme cases,” families can break up entirely with the children going into foster care.

“The impact on children here could not be clearer,” the brief stated.

Fear of deportation also drives families away from public spaces, the brief insisted, and thus harms the public interest.

“Amici have thousands of immigrants within their congregations and have seen how a lack of lawful presence can prevent individuals from positively contributing to their social, religious, and local communities,” the brief stated.

For example, the brief noted, a Mennonite pastor in Iowa and father of four had resided there for over 20 years before he was deported in 2015. He had been convicted of a DUI and trying to obtain a false driver’s license 16 years earlier, but since that time he had become pastor of a church and had ministered to drug addicts.

“The Immigration Guidance provides important benefits to those most vulnerable in our society and to those who serve them,” the brief concluded. “Because the Immigration Guidance provides substantial humanitarian benefits, it represents a valid exercise of the Secretary’s prosecutorial discretion the review of which is not justiciable.”