A federal judge in the United States has ruled the federal government's mass surveillance of the phone network is legal.
In a 53-page ruling dismissing a lawsuit brought by the American Civil Liberties Union, New York District Judge William Pauley said "the balance of equities and the public interest tilt firmly in favour of the Government's position.
"The right to be free from searches and seizures is fundamental, but not absolute," he wrote.
"Every day, people voluntarily surrender personal and seemingly-private information to trans-national corporations, which exploit that data for profit. Few think twice about it, even though it is far more intrusive than bulk telephony metadata collection.
"There is no evidence that the government has used any of the bulk telephony metadata it collected for any purpose other than investigating and disrupting terrorist attacks."
The ACLU said it will appeal against the ruling.
The BBC reports the ruling contradicts another on 17 December by Washington DC Federal Judge Richard Leon, who said the NSA's surveillance programme was "indiscriminate" and an "arbitrary invasion".
He backed a legal challenge on the merits of the Fourth Amendment, the clause in the US Constitution that bars unreasonable search and seizure by the government.
Collection of metadata by the NSA was exposed by Edward Snowden, a former contractor for the agency, who is now a fugitive in Russia.