The letters, the judge wrote, violate free-speech rights.
Judge Susan Illston also found that the government failed to show that the letters and the blanket non-disclosure policy "serve the compelling need of national security" and that the gag order they come with creates "too large a danger that speech is being unnecessarily restricted."
The EFF's vindication, it turns out, was to be short-lived.
That same judge has done an about-face, ordering Google to comply with the FBI's demand for information on certain users as part of a national security investigation, the AP reported on Saturday.
The FBI really, really likes NSLs. Between 2003-2006, it sent 192,499 data demand letters that contained gag orders, ensuring that surveillance targets are kept in the dark about their issuance.
According to AP, the latest data available shows that the FBI sent 16,511 National Security Letters about 7,201 people in 2011.
Judge Illston had put her March ruling on hold, giving the government the chance to appeal.
After receiving sworn statements from two top FBI officials, Justice Illston took the FBI's side in a 20 May ruling, commanding Google to comply with the data demands.
Google had contested the constitutionality and necessity of the letters, but Justice Illston said that she was now satisfied that 17 of 19 letters had been issued properly, though she wanted more information on the other two.
NSLs are legally limited to the request of non-content information, such as transactional records, phone numbers dialed, or email addresses to which a given surveillance target has mailed to or from. NSLs cannot demand content, so the content of Gmail message could not be requested, for example.
The judge's ruling doesn't specify the type of information the government wanted to force Google to cough up with the NSL. Nor was it even clear whom the government was targeting, given that Illston didn't mention Google in her order.
Proceedings were closed to the public.
But AP reports that the judge mentioned the "petitioner" as having been involved in a similar case filed on April 22 in New York federal court.
On Friday, AP obtained public records to the effect that on April 22, the federal government filed a "petition to enforce National Security Letter" against Google after the company refused to cooperate with its demands.
AP quoted Kurt Opsah, an attorney with the EFF, who said he was:
"...disappointed that the same judge who declared these letters unconstitutional is now requiring compliance with them."
This is only the latest victory for a government whose zest for surveillance seems insatiable.
Twitter's findings echoed Google's ownTransparency Report, which showed that surveillance of Gmail and other accounts has skyrocketed, with much of it being authorized without a search warrant.
And the demand for increased surveillance is by no means stopping with the spread of warrantless surveillance or increased use of NSLs.
In fact, the government in May started up a task force to prepare legislation that would put the screws on companies such as Facebook and Google, forcing them to install wiretapping back doors.
To my mind, Judge Illston's turnaround on the constitutionality of NSLs is just one more gold brick in what privacy advocates have dubbed the Golden Age of Surveillance.
Is that an unfounded assumption?
If so, perhaps the government might care to make hearings like this one public, shedding light on how essential these NSLs are. Or, perhaps, it might show that they represent an egregious affront to free speech and privacy rights.
As for Google, the company is owed our thanks for making an effort to keep user information out of government hands.