A U.S. District Judge ruled on Monday that the U.S National Service Agency (NSA) phone surveillance program as possibly illegal.

The security agency’s so-called metadata counter terrorism program, a program wherein the U.S. government is collecting personal information of its citizens without permission, was ruled unlawful in a court ruling.

U.S. District Judge Richard Leon, said in a 68-page court ruling, as reported by Reuters: “I cannot imagine a more 'indiscriminate' and 'arbitrary invasion' than this systematic and high-tech collection and retention of personal data on virtually every single citizen.”

Though the U.S. Justice Department “believe that [NSA’s phone surveillance] program is constitutional,” they are still going to review the court ruling brought by Larry Klayman, a conservative lawyer, Charles Strange the father of a cryptologist technician for the agency who was killed in Afghanistan in 2011.

While the DOJ is still reviewing the documents, they ordered the government to impede collecting information about Klayman and Strange, who were Verizon subscribers.

Meanwhile, Verizon Communications Inc. declined to comment about the issue.

Andrew Ames, a spokesperson for DOJ, said in a statement: “We believe the program is constitutional as previous judges have found.”

Judge Leon suspended the implementation of his decision against the program to give way for the “security interests at stake in this case and the novelty of the constitutional issues” until the government files an appeal.

A U.S. government official implied that an appeal is very possible.

However, Leon is uncertain of the program’s value, saying in the document that the government could not even give a single occasion wherein the bulk data actually prevented a forthcoming attack.

“I have serious doubts about the efficacy of the metadata collection program as a means of conducting time-sensitive investigations in cases involving imminent threats of terrorism,” he wrote.

Citing instances to justify the program is significant for it to be constitutional and authorized.