The suit filed in US District Court for the Northern District of California on Monday, a US government holiday, came as thousands of people rallied nationwide to protest against the Republican’s move last week.
In a statement, California Attorney General Xavier Becerra said the lawsuit alleges the Trump administration’s action violates the Constitution.
“President Trump treats the rule of law with utter contempt,” Becerra said. “He knows there is no border crisis, he knows his emergency declaration is unwarranted, and he admits that he will likely lose this case in court.”
Becerra had previously said his state and others had legal standing because they risked losing money intended for military projects, disaster assistance and other purposes.
Joining California in filing the lawsuit against the Republican president’s administration are the attorneys general of Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, Oregon, and Virginia.
Trump declared a national emergency after Congress declined to meet his request for $5.7bn to fulfil his 2016 election campaign promise of completing the wall.
The move allows the president to bypass Congress to use money from the Pentagon and other budgets.
The lawsuit against Trump on Monday argues he does not have the power to divert the funds because Congress is in charge of spending.
On Friday, three Texas landowners and an environmental group filed the first lawsuit against Trump’s move, saying it violates the Constitution and would infringe on their property rights.
The legal challenges could slow down Trump’s efforts to build the wall, which he says is needed to check irregular immigration and drug trafficking, but will likely end up at the conservative-leaning Supreme Court.
Several Republican senators have decried the emergency declaration, saying it establishes a dangerous precedent and amounts to executive overreach.
“President Trump is manufacturing a crisis and declaring a made-up ‘national emergency’ in order to seize power and undermine the Constitution,” California Governor Gavin Newsom said in a statement on Monday.
“This ’emergency’ is a national disgrace.”
However, John Fredericks, a syndicated radio talk show host and member of the Trump 2020 campaign advisory board, said Trump’s declaration is justified.
“This is an emergency and the president is ultimately going to be successful in securing about an additional $8bn towards the barrier and the wall that he’s advocated for,” Fredericks told Al Jazeera.
“This is a frivolous lawsuit brought by the 16 democratic states that basically want an open border situation so they can have additional people come into the US – undocumented, illegal and eventually turn into Democratic voters. That’s what this argument is about. Everybody sees through it.
“The amount of illegal immigration crossings with these caravans coming up is increased dramatically. We have gangs, we have violence, we have drugs,” Fredericks added.