Google has filed a rare petition to challenge a national security letter issued by the government to obtain private data about one or more of its users, Wired reports.

The petition, filed under seal in the U.S. District Court of Northern California on March 29, comes mere days after a U.S. District Judge in California ruled in a case brought by an unnamed company and the Electronic Frontier Foundation that so-called NSLs that come with a gag order on the recipient are an unconstitutional impingement on free speech, the article says.

It is not known when exactly Google received the NSL or why the company is fighting back against this particular one, although the recent ruling likely emboldened the company.

In early March, Google signaled an interest in becoming more transparent about the NSLs is has received by releasing a report showing a “range” of times that it received NSLs from the FBI, Wired reports.

According to the article: “The search giant published the information only after negotiating an agreement with the federal government that it would only publish a vague range indicating the number of times it received NSLs. The report indicated only that Google had received somewhere in the range of 0 and 999 NSLs each year between 2009 and 2012. Though the numbers were too broad to be useful, they signaled an interest by the search giant to provide an accounting of NSLs that has been missing since the government began using the orders prolifically after 9/11.

“In filing its recent court challenge, Google has joined a very small club of NSL recipients who have taken on the civil liberties interests of users by fighting back against orders that until now have been issued under the cloak of secrecy and generally without oversight.”

NSLs have been in use for decades but were expanded under the Patriot Act. They are written demands from the FBI compelling Internet service providers, credit companies, financial institutions and others to hand over confidential records about their customers, such as subscriber information, phone number and email addresses, websites visited and more. NSLs do not require court approval and, until now, most came with a built-in gag order.

You can read Wired’s full report on the history of NSLs here