Protesters speak out against Trump administration immigration policies Monday at the Statehouse in Montpelier. Photo by Jim Welch/VTDigger

[A]ttorney General TJ Donovan joined a lawsuit arguing that a policy that has forced the separation of immigrant parents and children at the southwest border is unconstitutional.

Vermont joined 16 other states and Washington, D.C., in filing the suit against the Trump administration in federal court in western Washington state Tuesday.

The Trump administration adopted a new “zero tolerance” approach to cracking down on people who enter the country illegally over the southwest border in May.

The policy required all adults to face criminal prosecution and be held in federal prisons. Because children cannot be held in prison, they were separated from their parents and held in detention centers, foster care or other locations around the country.

The Trump administration has called on Congress to pass a law to change the situation, saying it is up to lawmakers. However, interpretation of the current law falls within the administration’s discretion.

Trump ordered the end of the policy last week, but thousands of children remain separated from their parents.

The states write in the suit that the administration adopted the separation policy “for the express purpose of deterring immigration along the Southwestern border.”

They argue that the order Trump signed last week that the administration said would end separations is “illusory” and doesn’t end the practice.

The case asserts that the policy violates the parents’ and children’s constitutional right to due process. They also argue that the policy is discriminatory and violates equal protection rights, in that it only targets those who cross the southern border.

The policy is not in place for those who cross over the northern border.

The lawsuit argues that the policy violates states’ sovereign and proprietary interests.

Vermont has “fundamental, sovereign interest” in the well-being of children, which gives the state the right to intervene when there are issues, the suit states.

In remarks prepared for a Statehouse rally protesting the policy Monday, Donovan called the policy “simply wrong.”

“Our country has always been a refuge for people who are fleeing violence and danger and come here for a better life for their families,” he wrote. The statement was read out by a member of the office’s staff.

Twitter: @emhew. Elizabeth Hewitt is the Sunday editor for VTDigger. She grew up in central Vermont and holds a graduate degree in magazine journalism from New York University.