The American Civil Liberties Union (ACLU) filed the lawsuit against the Trump administration on behalf of the Sierra Club and Southern Border Communities Coalition, challenging the government's recent decision to allocate $3.8 billion in military funds for border wall construction.
"Neither a declaration of emergency nor the military funding statutes the administration has invoked permit the executive branch to disregard Congress's enacted appropriations legislation," the complaint said. "The executive branch has no authority to spend money without congressional approval, and its continuing efforts to do so are unlawful and violate the Constitution."
Congress recently granted the Trump administration $1.4 billion in border wall funding for fiscal year 2020.
The Trump administration previously transferred more than $6 billion in military funding for border wall construction in fiscal year 2019. However, a US court in California found that it was unlawful.
The administration's appeals of those rulings are still pending in the Ninth Circuit Court of Appeals. The first hearing is scheduled on March 10.