Sixteen states in the United States on Monday filed a lawsuit challenging President Donald Trump’s national emergency declaration in order to fund a wall along the Mexico border, CNN reported.

The group of states led by California Attorney General Xavier Becerra filed the lawsuit in the US District Court for the Northern District of California. “We’re going to try to halt the President from violating the Constitution, the separation of powers, from stealing money from Americans and states that has been allocated by Congress, lawfully,” Becerra said.

Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, Oregon and Virginia have joined the lawsuit.

The lawsuit argued that Trump does not have the power to divert funds to construct a wall along the border since Congress controls spending, The New York Times reported.

Trump had declared a national emergency on Friday to get funds for the wall after the Congress refused to grant the money he wanted. Trump had sought $5.7 billion for the wall. He believes the wall will help curb crime and drug trade in the US.

The Judiciary Committee of the House of Representatives has started an investigation into the move. The House is controlled by the Democratic Party, which has opposed the border wall.

Three Texas property owners and an environmental group filed the first lawsuit against Trump’s move on Friday, saying it violated the Constitution and would infringe on their property rights, Reuters reported.

The wall was one of the main promises of the Trump election campaign in 2016. The disagreement between the two parties over funding the wall ended up in the longest government shutdown in December-January. The shutdown ended when Trump signed a deal on January 25 to give the Congress 21 days to come up with an agreement or face further blocking of funds.