Google is taking on the full might of the US government in what will be a milestone court case, launching a legal challenge against the FBI’s warrantless electronic data-gathering technique – the first time a major communications company has taken such action, Bloomberg reports.

The case relates to Google’s apparent refusal to comply with a National Security Letter (NSL), which is a common method employed by the FBI to request the “name, address, length of service and other information” from internet users without the need for a warrant, albeit only in cases of national security. The FBI can make the request without any court authority whatsoever, and companies are not allowed to disclose that the request has been made to the users concerned, says the Electronic Frontier Foundation. Google’s move comes just three weeks after a federal judge ruled that NSLs were unconstitutional.

Law enforcement officials are believed to have issued more than 300,000 NSLs since they were given the power to do so in 2000. Last month, Google for the first time disclosed information about the number of NSL requests that it had received, saying that more than 1,000 of its user’s accounts had been affected.

According to Bloomberg, Google has filed a petition pursuant to “18 U.S.C. Section 3511 (a) and (b)”, according to a petition filed at the federal court in San Francisco asking the court to seal its request.

Section 3511 (a) stipulates that telecommunications firms in receipt of an NSL are allowed to petition a federal judge to set aside that request, if the judge believes that compliance would be “unreasonable, oppressive or otherwise unlawful. Meanwhile, Section 3511 (b) allows recipients of NSLs to ask the judge to lift the gag order barring them from disclosing the details of the NSL request.

It’s likely that Google’s plea will find sympathetic ears – assigned to the case is none other than judge Susan Illston, the very same judge who ruled last month that NSLs are unconstitutional and ordered the FBI to stop using them. This order is subject to a 90-day appeal period, meaning that NSLs are still enforceable in theory, though it’s not clear if any government agency has tried to press the issue since then.