WASHINGTON — A coalition of 16 states, including California and New York, on Monday challenged President Trump in court over his plan to use emergency powers to spend billions of dollars on his border wall.
The lawsuit is part of a constitutional confrontation that Mr. Trump set off on Friday when he declared that he would spend billions of dollars more on border barriers than Congress had granted him. The clash raises questions over congressional control of spending, the scope of emergency powers granted to the president, and how far the courts are willing to go to settle such a dispute.
The suit, filed in Federal District Court in San Francisco, argues that the president does not have the power to divert funds for constructing a wall along the Mexican border because it is Congress that controls spending.
Xavier Becerra, the attorney general of California, said in an interview that the president himself had undercut his argument that there was an emergency on the border.
Congress is on its own separate track to challenge the president’s declaration. The House of Representatives, now controlled by Democrats, may take a two-prong approach when it returns from a recess. One would be to bring a lawsuit of its own.
Lawmakers could also vote to override the declaration that an emergency exists, but it is doubtful that Congress has the votes to override Mr. Trump’s certain veto, leaving the courts a more likely venue.
Joining California and New York are Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, Oregon and Virginia. All have Democratic governors but one — Maryland, whose attorney general is a Democrat — and most have legislatures controlled by Democrats.
The dispute stems from steps Mr. Trump said he would take after lawmakers granted him only $1.375 billion for new border barriers, legislation he signed last week to avoid another government shutdown.
Mr. Trump asserted the power to tap three additional pots of money on his own: $600 million from a Treasury Department asset forfeiture fund for law enforcement priorities; about $2.5 billion from a military antidrug account, most of which would first be siphoned from other military programs the Pentagon has yet to identify; and $3.6 billion in military construction funds he said he could redirect by invoking an emergency-powers statute.
Presidents have invoked emergency-powers statutes nearly five dozen times since Congress enacted the National Emergencies Act of 1976, but never before has one been used to make an end-run around Congress after it rejected funding for a particular policy.
But as the debate over Mr. Trump’s action shifts to courtrooms, legal experts warned that its fate may turn less on such high constitutional principle and more on complex legal issues — from whether plaintiffs can establish that the case is properly before the courts, to how to interpret several statutes.
“Even though Trump’s political maneuver to get around an uncooperative Congress looks like it stretches the Constitution, the questions presented in court will raise ordinary and complicated issues of administrative law,” said Peter M. Shane, an Ohio State University law professor and co-author of a separation-of-powers casebook.
Two cases had already been filed after Mr. Trump’s announcement on Feb. 15 — one by the nonprofit watchdog group Public Citizen, representing several Texas landowners and a Texas environmental group, and the other a case jointly brought by the Center for Biological Diversity, Defenders of Wildlife and the Animal Legal Defense Fund.
At least two other lawsuits are expected to be filed later this week. The American Civil Liberties Union has announced its intention to file a case, but has not yet publicly identified its client. The other case will be brought by Protect Democracy, another watchdog group, and the Niskanen Center, a center-right policy institute, on behalf of El Paso County and the Border Network for Human Rights.
Many critics have challenged whether an emergency truly exists on the Southern border that a wall would solve, pointing to government data showing that the number of people crossing illegally has dropped significantly over the past generation and that most drugs are smuggled through ports of entry.
The president has argued, without proof, that the emergency declaration is warranted because the migrants “invading” the United States across the Mexico border have caused epidemics of crime and drug use.
Legal specialists expected the Justice Department to urge a court not to consider facts about the border or Mr. Trump’s words, but rather to defer to the president’s decision. The courts have a long history of being reluctant to substitute their own judgment for the president’s about a security threat.
The Trump administration will have a powerful argument to invoke: In the National Emergencies Act, Congress defined no standard for what conditions have to be met before a president may determine that a qualifying crisis exists.
But before a judge could weigh whether Mr. Trump invoked the statute legitimately, he or she would have to decide whether the dispute is properly before the court in the first place.
Plaintiffs will need to establish standing by showing that they are suffering some particular injury from what Mr. Trump is doing. Several of the lawsuits involve people who own land or represent communities along the Mexican border in Texas, where Mr. Trump has put the focus of his emphasis on the need for more barriers.
Mr. Becerra, California’s attorney general, suggested that plaintiffs in the states’ lawsuits have standing for reasons that are unrelated to whether any portions of Mr. Trump’s wall will be built in their territory, arguing that “the president’s unconstitutional action could cause harms in many parts of the country.”
People in California and other plaintiff states could “lose funding that they paid for with their tax dollars, money that was destined for drug interdiction or for the Department of Defense for military men and women and military installations,” he said in the interview.
Further complicating matters, the administration has said it intends to spend the funds in sequence, starting with the $1.375 billion Congress appropriated, and reaching the emergency-power military-construction fund last. The Justice Department is likely to argue that if no disputed spending is imminent, the case is not ripe for litigation and should be dismissed.
Ian Bassin, the executive director of Protect Democracy, said that El Paso County would probably argue that its economy was being harmed by Mr. Trump’s emergency declaration because it wrongfully signaled to businesses and potential tourists that they should stay away.
The Justice Department declined to comment on the wave of lawsuits. Mr. Trump has said he expected to be sued and to lose in lower courts, but he predicted he would eventually prevail before the Supreme Court.
But plaintiffs can also challenge whether the administration is interpreting several statutes correctly.
And the emergency-powers statute Mr. Trump plans to use permits military construction spending in an emergency that requires the use of the armed forces for projects “to support such use.” That has been used before to build up foreign military bases in a war effort, but litigants challenge whether a permanent wall to help civilian agencies police the border qualifies under that wording.
“Judges will certainly be aware of the larger institutional context when they address those technical issues, but that awareness will not, by itself, determine how the legal questions get resolved,” Mr. Shane said.