It was revealed that Yahoo’s top lawyers had a courtroom showdown with the National Security Agency after it had demanded information on certain foreign users without a warrant, but the tech giant lost and was forced to hand over the data.

Court documents obtained by the New York Times show that Yahoo had initially refused to join the PRISM spying program, insisting that the broad national security requests seeking users’ personal information were unconstitutional.

However, the secret court operating under the Foreign Intelligence Surveillance Act (FISA) sided with the NSA and forced Yahoo’s hand.

Information about Yahoo’s legal battle against the NSA first emerged in a heavily redacted court order, but the name of the company involved had not been released until now.

It was claimed that besides Yahoo, a number of major Silicon Valley companies became part of PRISM, among them Apple, Facebook, Microsoft, Google, YouTube, Skype, AOL and the lesser known Internet company PalTalk, which has hosted a lot of traffic during the Arab Spring and the on-going Syrian civil war.

However, only Facebook and Google have been shown to have worked toward creating “online rooms” in which to share data with the government.

Information about the classified program was leaked last week by NSA systems administrator Edward Snowden, 29, who smuggled the files concerning PRISM on a thumb drive.

Yahoo fought against NSA’s warrantless spying program but lost and was forced by secret court to join PRISM

In 2008, Yahoo argued that NSA’s requests seeking to obtain its users’ private data violated their Fourth Amendment rights against unreasonable searches and seizures, but the judges on the FISA court disagreed with the company’s assessment, calling their concerns “overblown”, the Times reported.

“Notwithstanding the parade of horrible trotted out by the petitioner, it has presented no evidence of any actual harm, any egregious risk of error, or any broad potential for abuse,” the court said, adding that the government’s “efforts to protect national security should not be frustrated by the courts”.

Yahoo’s defeat in court reportedly left other top players in the industry more reluctant to challenge the NSA on surveillance request.

So far, Yahoo, Google and Facebook have all denied their involvement in PRISM.

“Yahoo! has not joined any program in which we volunteer to share user data with the U.S. government,” Yahoo General Counsel Ron Bell wrote in a Tumblr post Saturday.

“We do not voluntarily disclose user information. The only disclosures that occur are in response to specific demands.”

In the wake of the unwarranted spying scandal, a number of top Silicon Valley companies, among them Facebook, Google and Microsoft, have asked the government to overturn a gag order allowing them to publicly disclose national security requests.

Google Inc was the first to go public with its demand for greater transparency, releasing an open letter asking the U.S. Department of Justice for permission to disclose the number and scope of data requests each receives from security agencies, including confidential FISA requests.

Microsoft Corp and Facebook Inc soon followed with similarly worded statements in support of Google.

Last year, the US government issued more than 1,850 FISA requests and 15,000 National Security Letters, which refers to requests filed by the FBI to collect information about Americans.

Between 2008 and 2012, only two of more than 8,500 FISA requests were rejected by the secret court, according to the Electronic Privacy Information Center, a non-profit research group.