US state of California suing President Donald Trump administration over border wall

California Atty. Gen. Xavier Becerra (AP)

The US state of California will announce a lawsuit that will challenge President Donald Trump’s proposal to build a wall along the US-Mexico border, a project the state’s attorney general has called “medieval.”

The lawsuit filed Wednesday alleges that the Trump administration has failed to comply with federal and state environmental laws, relied on federal statutes that don not authorize the proposed projects and violates the US Constitution's separation of powers doctrine.

The lawsuit also says the US Department of Homeland Security decided to build the wall without complying with the Clean Water Act and National Environmental Policy Act, hence the 2,000-mile-long (3218  km) project lacks proper environmental measures.

"They're violating the Tenth Amendment and infringing on a lot of state laws, not just federal laws, that effect our state. At the same time, they're trying to do something that only Congress can do," California Attorney General Xavier Becerra told journalists in Washington in advance of an official announcement he plans to make in San Diego Wednesday.

Becerra said the suit will argue that federal officials are running afoul of the law by declaring the expansion of the border wall to be an emergency that justifies waiving environmental studies and usual contracting procedures.

The Democratic attorney general has been critical of the wall for months. In April, during an appearance on ABC's “This Week,” he said: “I’m still trying to figure out who believes a medieval situation to fix the immigrant situation is what we need.”

State Senator Ricardo Lara authored the bill, testifying at a committee hearing that "the wall is another attempt to separate and divide us. It sends a message that we are better off in a homogeneous society."

During the 2016 presidential campaign, Trump said the US would build a wall on the US-Mexico border to keep illegal immigrants from entering the country. The Mexican government has strongly criticized the proposal.

Trump has insisted Mexico would pay for building the wall, which experts said could cost about $22 billion and take more than three years to complete.

With Mexico refusing to pay, Trump has said that the wall will initially need US funding but that he will find a way to make Mexico ultimately pay for it.