Google cited a provision that allows judges to modify or deny National Security Letters that are “unreasonable, oppressive or otherwise unlawful.”
Michelle Richardson, legislative counsel for the American Civil Liberties Union, said in an email that Google's stance is "groundbreaking," and is the first publicly available example of a company fighting a National Security Letter.
She said Google's resistance is "important because on a practical level, it's those types of companies that are receiving the overwhelming majority of [National Security Letters] in the first place."
"This request really must be unprecedented in some way, perhaps for vast amounts of internet information, or internet information that is particularly sensitive," she said.
Google declined to comment on the filing.
Last month, Google revealed that for each of the past four years, it has received fewer than one thousand National Security Letters. Those requests covered data on between 1,000 and 1,999 user accounts, except for 2010, when the requests covered between 2,000 and 2,999 accounts, according to Google.
In a blog post, Richard Salgado, Google's director of law enforcement and information security, said the company worked with government officials to provide greater insight into the National Security Letter process.
He said the company had to provide numerical ranges instead of exact figures to address the concerns raised by the FBI, the Justice Department and other agencies that exact numbers could reveal information about sensitive investigations.
—Updated at 12:37 p.m.