A coalition of 16 states filed a federal lawsuit Monday to block President Trump’s plan to build a border wall without permission from Congress, arguing that the president’s decision to declare a national emergency is unconstitutional.

The lawsuit, brought by states with Democratic governors except for one — Maryland — seeks a preliminary injunction that would prevent the president from acting on his emergency declaration while the case plays out in the courts.

The complaint was filed in the U.S. District Court for the Northern District of California — a San Francisco-based court whose judges have ruled against an array of other Trump administration policies, including on immigration and the environment.

Accusing the president of “an unconstitutional and unlawful scheme,” the suit says the states are trying “to protect their residents, natural resources, and economic interests from President Donald J. Trump’s flagrant disregard of fundamental separation of powers principles engrained in the United States Constitution.”

The complaint, filed by the attorneys general of nearly a third of the states and representing millions of Americans, immediately becomes the heavyweight among a rapid outpouring of opposition to the president’s emergency declaration. In the White House Rose Garden on Friday, Trump announced that he was instituting a national emergency at the U.S.-Mexico border because Congress did not provide the money for a wall that has stood as one of the most enduring promises from his 2016 campaign.

Several nonprofit organizations already have gone to court or announced plans to sue. And protesters took to the streets in several cities on Monday. Across from the White House, demonstrators held neon-colored letters that spelled, “POWER GRAB.”

Demonstrators hold signs during a demonstration organized by the American Civil Liberties Union (ACLU) protesting President Donald Trump's declaration of emergency powers on February 18, 2019 in Washington, DC. (Zach Gibson/Getty Images)

“You wouldn’t expect to celebrate Presidents’ Day this way, but we do what you got to do,” California Attorney General Xavier Becerra (D), leader of the states coalition, said Monday in an interview. “In this case, we are having to commemorate . . . by protesting, whether marching in the street or marching into court.”

Through the president’s declared emergency, White House officials plan to use $8 billion to build sections of a barrier that Trump says will obstruct or deter migrants from crossing into the country. That sum is about $6.6 billion more than Congress allotted for the purpose in its latest spending plan. To fill in the gap, the White House intends, among other things, to divert $3.6 billion from military construction accounts and $2.5 billion from Department of Defense efforts to fight illicit drugs.

In the 56-page complaint, Becerra and his counterparts argue that diverting money that Congress has designated for other purposes violates the separation of powers defined in the Constitution.

The complaint says that once Congress passes laws and a president signs them, the Constitution requires that the president “take care that the laws be faithfully executed.” Another clause of the Constitution, the lawsuit says, prevents money from being paid from the U.S. Treasury unless Congress has appropriated it.

The lawsuit also alleges that the “federal government’s own data prove there is no national emergency at the southern border that warrants construction of a wall. Customs and Border Protection data show that unlawful entries are near 45-year lows.”

A demonstrator holds an American flag in Lafayette Square during a demonstration organized by the American Civil Liberties Union (ACLU) protesting President Donald Trump's declaration of emergency powers on February 18, 2019 in Washington, DC. (Zach Gibson/Getty Images)

And it enumerates ways that residents of the participating states — and the states themselves — could be harmed by the diversion of funds.

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In addition to California, the states participating in the suit are Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, Oregon and Virginia. With the exception of Maryland Gov. Larry Hogan (R), the governors of the states are Democrats.

The suit names as defendants the president, the departments of Defense, Treasury, Interior and Homeland Security and senior officials of those departments.

In filing the case in the San Francisco-based Northern District, the attorneys general chose a jurisdiction that has repeatedly been at odds with the president. According to a count by The Washington Post, the court’s judges have ruled against the Trump administration in at least nine important cases.

Judges there, for example, have ruled against efforts by the Commerce Department to add a citizenship question to the 2020 census, numerous rollbacks of environmental regulations, efforts to curtail asylum for migrants and the Department of Homeland Security’s revocation of special “temporary protected status” for hundreds of thousands of immigrants legally living in the U.S.

Cases appealed from that court go to the U.S. Court of Appeals for the 9th Circuit, which has become a whipping post for Trump, who has derided it as “a complete and total disaster” and “a thorn in our side.”

Since the president’s announcement, GOP members of Congress have had mixed opinions of the declaration, with some contending it is legitimate and others portraying it as a power grab that could create a dangerous precedent in the event of a future Democratic president.

Congressional Democrats plan to vote in coming weeks on a joint resolution that would repeal the national emergency, and they predict that some Republicans will support it.

Trump has said his declaration is allowed under a 1976 law called the National Emergencies Act and that it has been used dozens of times. Outside analyses, including by the Brennan Center for Justice, have shown that virtually all such emergencies involved sanctions against foreign governments and groups for reasons such as human rights violations, rather than to spend money Congress intended for other purposes.

President George W. Bush declared a national emergency soon after the 9/11 terrorist attacks, but the spending it allowed had not previously been designated by Congress for other purposes.

On Friday, Public Citizen and the Center for Biological Diversity filed separate lawsuits in the U.S. District Court for the District of Columbia, alleging that Trump’s emergency declaration is unconstitutional.

Another advocacy group, Citizens for Responsibility and Ethics in Washington, sued the Justice Department on Friday, accusing it of failing to provide legal opinions, communications and other documents related to the president’s decision to declare a national emergency.