No telecommunications company has ever challenged the secretive Foreign Intelligence Surveillance court's orders for bulk phone records under the Patriot Act, the court revealed on Tuesday.

The secretive Fisa court's disclosure came inside a declassification of its legal reasoning justifying the National Security Agency's ongoing bulk collection of Americans' phone records.

Citing the "unprecedented disclosures" and the "ongoing public interest in this program", Judge Claire V Eagan on 29 August not only approved the Obama administration's request for the bulk collection of data from an unidentified telecommunications firm, but ordered it declassified. Eagan wrote that despite the "lower threshold" for government bulk surveillance under Section 215 of the Patriot Act compared to other laws, the telephone companies who have received Fisa court orders for mass customer data have not challenged the law.

"To date, no holder of records who has received an Order to produce bulk telephony metadata has challenged the legality of such an Order," Eagan wrote. "Indeed, no recipient of any Section 215 Order has challenged the legality of such an order, despite the mechanism for doing so."

That complicity has not been total. Before the Bush administration moved the bulk phone records collection under the authority of the Fisa court, around 2006, Qwest Communications refused to participate in the effort.

Telecommunications company acquiescence to the bulk phone records collection orders also contrasts with the protestations of some internet companies regarding their relationship with the NSA. Yahoo is petitioning the Fisa court to disclose a 2008 incident in which it refused to comply with bulk NSA surveillance until the court demanded it turn over customer data.

While the director of national intelligence, James Clapper, in July declassified a Fisa court order underpinning the bulk phone records collection, the order declassified on Tuesday delved far deeper into the reasoning used by the court to justify the mass collection under Section 215, allowing the government to access data "relevant" to an "ongoing" terrorism investigation.

The disclosure is the third major court disclosure about bulk surveillance in a week. On Friday, the Fisa court – citing the public interest in surveillance generated by the former NSA contractor Edward Snowden – ordered the government to review for potential declassification post-2011 court opinions related to the phone records database.

Tuesday's ruling presented one such opinion – one that found the court in substantial agreement with the government's interpretation of its powers under the Patriot Act.

Citing a supreme court precedent, Eagan found that there are no Fourth Amendment protections around so-called "metadata", the records of phone numbers dialed and received or the times and durations of phone calls. While the precedent, Smith v Maryland, had to do with an individual case, Eagan wrote that the collection of metadata from millions of people does not, en masse, create a constitutional problem.

That contention is the subject of court challenges by the American Civil Liberties Union (ACLU) and other groups.

Eagan's August 2013 order also shed light on how the court considers mass phone records from Americans not under suspicion of wrongdoing "relevant" to an "ongoing" terrorism investigation.

"The government's burden under Section 215 is not to prove that the records sought are, in fact, relevant to an ongoing investigation," Eagan wrote; merely that the government must have "reasonable grounds to believe that the information sought to be produced has some bearing on its investigations of the identified international terrorist organizations."

The judge assented to the government's argument that the necessity underpinning the bulk phone records collection was "to create a historical repository of metadata that enables NSA to find or identify known or unknown operatives", including inside the United States.

But Eagan recognized that "the concept of relevance here is in fact broad and amounts to a relatively low standard".

Civil libertarians found the Fisa court judge's reasoning alarming.

"It's problematic because it means the government is allowed to collect records merely in anticipation of investigations," said Patrick Toomey, a lawyer for the ACLU.

Kurt Opsahl, a lawyer with the Electronic Frontier Foundation, said: "There's not much daylight between what the government asserts and what the court determines."

While Opsahl hailed the court for disclosing more information about its inner workings, he said the ruling "shows the trouble with having a one-sided court process, where the court is only seeing arguments from one side and seems to adopt those arguments. It seems like a failure of the adversarial process."

The Fisa court does not hear from any petitioner aside from the government. Bills currently before Congress would create a privacy advocate to push back against the government's arguments before the Fisa court.

Sheldon Snook, a spokesman for the Fisa court, said Tuesday's disclosure marked the first time the secret court had decided on its own to reveal information related to the NSA's phone records database.

In a statement on Tuesday, Clapper said the August court opinion "affirms that the bulk telephony metadata collection is both lawful and constitutional".

"The release of this opinion is consistent with the president's call for more transparency on these valuable intelligence programs," Clapper said.