By Agence France-Presse
The first hearing on two lawsuits filed in Oakland, California challenging the declaration adjourned after dealing with procedural issues, with the judge giving no indication of when a ruling may be handed down.
About 20 states, including Democratic strongholds New York and California, along with the American Civil Liberties Union (ACLU), environmental groups and border communities are involved in the suits, which claim the emergency declaration violates the constitution.
"We are hopeful that today's hearing stressed what is truly at stake with Trump's border wall -- the endangerment of communities and destruction of our environment," said Gloria Smith, managing attorney at the Sierra Club, one of the plaintiffs.
Trump made the construction of a wall to stem illegal immigration from Latin America central to his successful 2016 campaign for the presidency.
But despite saying Mexico would pay for the barrier, he's had to ask Congress for $3.6 billion in funding to make the project happen, along with an additional $2.5 billion to fight drug traffickers.
The tug-of-war over funding for the barrier caused a record 35-day federal government shutdown beginning on December 22, 2018, and lawmakers have thus far allocated only $1.4 billion to pay for fencing and other barriers along the border.
Following the hearing, Dror Ladin, staff attorney at the ACLU's national security project said, "It was striking to hear the government claim out loud in court that Congress never denied Trump funding for his wall. That is patently wrong."
The lawsuits question the urgency of Trump's emergency declaration, and asks the court to halt wall construction work that the Defense Department said could start as soon as May 25.
It also claims the government violated environmental protections by failing to assess the impact of the wall's construction in California and New Mexico.
Among the plaintiffs' evidence are statements Trump made at his press conference following the emergency declaration where he said, "I could do the wall over a longer period of time," and "I didn't need to do this, but I would rather do it much faster."