The National Security Agency (NSA) has finally admitted to tracking the cell phone location of Americans. For two years, in 2010 and 2011, the spy agency ran an “experiment” pilot project in which they wanted to test how location information would flow into their massive databases containing other information on Americans.

As the New York Times reported on Wednesday, “it was unclear how many Americans’ locational data was collected as part of the project, whether the agency has held on to that information or why the program did not go forward.”

What’s clear to us is this was a massive invasion of privacy.

Cell phone location data is among the most sensitive data your cell phone emits, perhaps even more so than the phone metadata the NSA already collects, which is already incredibly invasive. Cell phones, which many Americans carry on them wherever they go, create a rich data trail of your movements over weeks or months at a time. With access to such data, the government could learn your most intimate daily habits, movements, and whereabouts—information many people’s closest friends and family would not even know.

During a Senate hearing last week, NSA chief Keith Alexander was whether the NSA has ever vacuuming up cell phone location data, or formulated any plans to do so. Alexander replied “Under Section 215, NSA is not receiving cell site location data and has no current plans to do so.” Referring to only Section 215 in his answer is NSA’s tried-and-true way of deflecting about collections they may be doing under other programs or legal authorities, and this week's admission underscores that point. Notice Alexander only referred to the Section 215 program and current activities, not past.

“Under this program” is the usual dodge used by the NSA (which we’ve documented before) to hide that they can get similar information using a different legal authority or under another one of their many surveillance “programs.” You’ll notice anytime the NSA is talking about whether they collect cell phone location information they always remember to add “under this program,” or in this case, specifically “under Section 215.”

This week, after admitting to the past collection, Director of National Intelligence (DNI) James Clapper told Congress they would tell the intelligence committee and FISA court if they restarted their location collection program—yet that means it would still stay secret from the American people. Despite these empty assurances, the NSA also claims it already has the legal authority to restart its location collection program at any time, they would simply be “informing” to secret bodies of their decision.

Wyden remarked to the New York Times after the hearing that the NSA is still not telling the whole story: “once again, the intelligence leadership has decided to leave most of the real story secret—even when the truth would not compromise national security.”

If there’s anyone we should believe, it’s Wyden, whose warnings about NSA privacy violations have again and again and again proven to be accurate with the release of new documents (whether by leaks or via EFF’s Freedom of Information Act lawsuits). Last week he went so far as to say the NSA “has repeatedly deceived the American people.”

For months, Wyden has been particularly insistent on the issue of cell phone location information. In a speech he gave in July, he explained that no matter what the NSA is doing right now, the agency believes it has the legal authority to mass collect location information whenever it wants.

During Director of National Intelligence James Clapper’s now infamous appearance before the intelligence committee in March—where he admittedly lied about the NSA collecting data on millions of Americans—Wyden’s money question was directly preceded by grilling Clapper about cell phone location information (read the full exchange here).

Sen. Wyden has been attempting to pass a bill that would require a warrant for cell phone location tracking for a long time. EFF has been involved in court cases around the country attempting to convince courts that cell phone location is protected by the Fourth Amendment. And some states have already taken the lead and have passed laws requiring a warrant for cell location information since the NSA’s “pilot program” allegedly ended in 2011.

It now more important than ever that courts recognize this right and that Congress acts fast before another database at Ft. Meade headquarters fills up with locations of millions of American with little restriction.