Attorney General Mark Herring (D-Va.) has joined 19 other attorneys general in filing a lawsuit against the Trump administration over its attempt to circumvent a longstanding rule designed to guarantee the safe and humane treatment of children in immigration custody.

The 1997 Flores Settlement Agreement limits the detention of migrant children to 20 days, but the Trump administration has said it intends to create new rules that would allow it to detain children for longer periods. 

In a lawsuit filed in the U.S. District Court for the Central District of California, Herring and a coalition of attorneys general argued that the administration’s new approach eliminates several critical protections guaranteed by the Flores agreement. Their flagship concern, as Herring explained in a statement, is that prolonged detentions will cause irreparable harm to the children and their families. 

Herring and his colleagues argued that the Trump administration’s plan undermines state licensing requirements for the facilities where children are held, thus interfering with the states’ abilities to protect the children. The new rule would also lead to an expansion of family detention centers, which are not licensed by the state, and have caused increased trauma in children, according to Herring’s statement. 

Earlier this year, Herring and the coalition of attorneys general succeeded in forcing the Trump administration to provide detained children with personal hygiene products, such as soap and toothpaste. 

In this lawsuit, Herring is joined by the attorneys general of California, Massachusetts, Connecticut, Delaware, Illinois, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, and the District of Columbia.