Colorado and 16 other states have filed a brief for their lawsuit challenging the Trump administration for terminating the Deferred Action for Childhood Arrivals program.

Attorney General Phil Weiser announced in March that the state was joining the lawsuit, which puts the 17,300 Colorado residents in the program at risk for deportation.

The brief, filed last week, argues that the decision to repeal the program was unlawful due to “demonstrably incorrect factual assumption and a glaring misstatement of law.” The petitioners who put forth the legal argument to terminate the program failed to properly investigate its merits, the brief claims.

“Crucial questions about petitioners’ decisional process remain unanswered, including what steps petitioners took to investigate how DACA operates and what information those steps revealed,” the brief says.

DACA has been a “regular practice” that has operated lawfully for decades, the brief says.

“The decision to terminate DACA was a dramatic policy reversal that threatened devastating consequences for hundreds of thousands of people, and serious harm to many thousands of employers and the economies and institutions of every state,” the brief says.

Weiser has personal and professional stake in the lawsuit.

“For me, this is a personal issue,” Weiser said. “My mom was an immigrant. The idea we would demonize and scare people who have lived their whole lives here, it’s wrong.”