A new border barrier is built near downtown El Paso, Texas, on Jan. 22, 2019. (AP photo/Eric Gay)

WASHINGTON (CN) – Urging a federal judge to freeze funds earmarked for a wall at the Southern border, a lawyer for the House of Representatives argued Thursday that the president’s reallocation of money in the defense budget violated congressional authority.

“This is going to the very heart of our checks and balances,” House attorney Douglas Letter said this morning in court. “We cannot have the president appropriating money.”

After Congress denied funds for a border wall, President Donald Trump declared a national emergency in February to tap into $3.6 billion from military construction accounts. Invoking other authority to access another $3.1 billion in federal funds, Trump freed up $8.1 billion to spend on the wall. Treasury officials put the plan into action a month later, transferring $1 billion set aside in the 2019 federal budget for military construction projects to an account for counter-narcotics support that previously contained $517.71 million. Plans for a second transfer of $1.5 billion are also in the works.

Under Democratic control this year following the 2018 election, the House filed suit over the move April 5.

At Thursday’s hearing before U.S. District Judge Trevor McFadden in Washington, Letter quoted Acting White House Chief of Staff Mick Mulvaney as saying the Trump administration would build a wall “with or without Congress.”

Letter ridiculed the government’s claim that the transfer was within its power under the 2019 Department of Defense Appropriations Act, which allows for funds to be transferred for “higher priority items, based on unforeseen military requirements.”

Given how Trump prioritized the wall early on the campaign trail and more recently when he shut down the government in an unsuccessful bid to get his funding, Letter said the construction of a border wall is hardly an “unforeseen” project.

Justice Department lawyer James Burnham argued meanwhile that the administration acted lawfully under the Appropriations Act. Making the case as well that the House cannot sue the executive branch, Burnham said that a congressional veto is the only course of action available for lawmakers to curb the president.

It is only because Republicans control the Senate, Burnham added, that the House lacks the political power to enforce this most “potent tool.”

“The framers hardly intended this political arm wrestling in the courts,” said Burnham.

Urging the judge to hold off on a ruling, Burnham noted that Acting Defense Secretary Patrick Shanahan is still considering how the money will be used for military operations on the Southern border.

“Your honor can’t put the money back in the Treasury,” Burnham said.

Letter emphasized in his rebuttal that the president has made clear the funding will be spent building a wall at the Southern border.

“I don’t think we would even be here of the president was just saying, ‘Everyone relax, I’m just putting a little fence around this military base.’”