Sixteen states joined together to file a federal lawsuit on Monday arguing that President Donald Trump’s declaration of a national emergency is unconstitutional.

The Washington Post reported that the lawsuit was filed in U.S. District Court for the Northern District of California. The states that have now joined the suit are New York, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Minnesota, Nevada, New Jersey, New Mexico, Oregon, Virginia and Michigan.

After failing to obtain congressional support for a spending bill that included $5.7 billion in funding to begin building a wall along the U.S.-Mexico border, then signing a bill that included $1.375 billion for border security, the president declared a national emergency last week so he could go around the legislative branch to secure billions more that he says is needed to start work on the barrier.

“Contrary to the will of Congress, the President has used the pretext of a manufactured ‘crisis’ of unlawful immigration to declare a national emergency and redirect federal dollars appropriated for drug interdiction, military construction and law enforcement initiatives toward building a wall on the United States-Mexico border,” the lawsuit states. The suit also alleges Trump has veered the country toward “a constitutional crisis of his own making,” adding that a national emergency declaration is not necessary, by the president’s own admission.

When making the declaration last week, Trump admitted he “didn’t need to” declare a national emergency to build the border wall, but he wanted to “do it much faster.” Critics quickly noted the president’s own words could be used against him in court.

California Attorney General Xavier Becerra led the coalition of states to file the suit, tweeting on Monday that they are challenging Trump’s ”#FakeNationalEmergency,” which he described as a “brazen overreach to rob taxpayers & an insult to the Democratic principles enshrined in our Constitution.”