Before intelligence contractor Edward Snowden leaked information on the government’s dragnet collection of phone call records, Sen. Ron Wyden, D-Ore., had tried to alert the public to the program’s existence. Unable to discuss classified operations, for years Wyden had been relegated to issuing vague warnings about the government’s spying programs. “When the American people find out how their government has secretly interpreted the Patriot Act,” Wyden said in May 2011, for example, “they will be stunned and they will be angry.”

But there is speculation that Wyden may not be done dropping hints. As a member of the Senate Intelligence Committee with knowledge of the National Security Agency’s operations, recently the senator has been talking a lot about tracking people’s locations through their cell phones. The NSA, Wyden has pointed out repeatedly, has the authority to collect location information on Americans' cell phones.

The frequent references to cell phone location data -- coupled with the government’s careful denials of location tracking -- have caused privacy and civil liberties advocates to wonder if the NSA is secretly collecting location information as well.

Since Snowden revealed that the government was collecting, in bulk, so-called metadata on virtually all Americans’ phone calls -- the originating and dialed numbers, time and duration of a call -- government officials have been adamant that the location of the calls is not collected, as they have said many times, “under this program.” But Wyden, along with a fellow critic of the government’s spying operations, Sen. Mark Udall, D-Colo., continues to press the issue of location tracking.

In a speech last week at the Center for American Progress, a liberal think tank, Wyden mentioned cell phone location data enough times that observers felt it could not be coincidence. “Under the classification rules observed by the Senate we are not even allowed to tap the truth out in Morse code,” Wyden said, according to his prepared remarks, explaining how difficult it is to alert the public to the existence of classified programs. “And we tried just about everything else we could think of to warn the American people.”

Wyden then immediately issued another sort of warning. “As you listen to this talk, ponder that most of us have a computer in our pocket that potentially can be used to track and monitor us 24/7,” he said.

Julian Sanchez, a privacy expert at the libertarian Cato Institute, took the speech as a sign. “Wyden’s constant references to location tracking in this context would be nothing short of bizarre unless he had reason to believe that the governments assurances on this score are misleading, and that there either is or has been some program involving bulk collection of phone records,” Sanchez wrote in a blog post Tuesday.

The speech isn’t the only time Wyden has raised the issue in recent days. Back in June, Wyden and Udall sent a letter to Director of National Intelligence James Clapper with a series of questions regarding the NSA programs, including, “Has the NSA collected or made any plans to collect Americans’ cell-site location data in bulk?” On Friday, Clapper responded that the government is not doing so, nor has it made any plans to do so “under this program.” Clapper added that the authority to collect the data does exist and that the director of the NSA would notify Congress if such a program began. He then directed Wyden and Udall to the classified supplement that accompanied the public letter for further information.

This answer, and whatever was contained in the classified response, did not satisfy Wyden and Udall, who blasted intelligence officials for not being straight with the American public. “This response leaves our question of past plans unanswered,” they said in a joint statement after receiving Clapper’s response. “Their violations of the rules for handling and accessing bulk phone information are more troubling than have been acknowledged and the American people deserve to know more details.” It is “deeply troubling,” they said, that the NSA “claims the authority” to collect cell-site information in bulk.

Even if the government is not now collecting cell phone location data in bulk, as Wyden and Udall are constantly reminding the public, it could do so at any time. The legal authority for the phone data sweep comes from section 215 of the USA Patriot Act, often called the “business records” provision, which authorizes collecting personal records considered relevant to a national security investigation. The Foreign Intelligence Surveillance Court, the secret body that approves surveillance requests, made this bulk collection possible by reinterpreting the use of the “relevance” standard to justify collecting an essentially infinite amount of information.

Under the government’s authority for collecting phone records, cell-site location data would also be fair game -- a position upheld by a federal appeals court this week, the highest court to rule on this issue. On Tuesday, the U.S. Court of Appeals for the Fifth Circuit ruled that a history of location information gathered by cell towers can be sought for an investigation without a warrant.

There are lots of ways that cell phones can be used to track location, but the Fifth Circuit was the first circuit court to decide that data retrieved from cell towers rather than, for example, through a phone’s GPS capabilities, is not protected under the Fourth Amendment. Cell phones connect to cell towers in order to make and receive calls, meaning that the phone companies know what cell tower was used for every call on their network and in most cases, what direction in relation to the tower that call came from. Tower data does not give exact location coordinates, but it is a good approximation of location.

The legal theory at issue here is called the third-party doctrine, which stipulates that information shared with a third party, like the phone company, is not protected by a “reasonable expectation of privacy” under the Fourth Amendment. These records can therefore be collected under section 215. The Fifth Circuit did not comment on bulk or ongoing collection, the most controversial features of the program revealed by Snowden. But the decision placed cell-site location data, which the opinion called “clearly a business record,” squarely in the same category of information as the phone metadata already being collected on all Americans by the NSA.

“Whether the intel community was looking to do bulk collection or very targeted acquisition of cell site location records, if the Fifth Circuit had gone the other way, they would not be able to do it pursuant to section 215,” said Mark Eckenwiler, a former Justice Department lawyer who focused on electronic privacy issues and had some involvement in this case.

Eckenwiler noted the swirling speculation around the government’s “fairly careful and narrow denials” about location tracking, including the use of the phrase “under this program” as “peculiarly carefully worded.” Without speculating on what the government might be doing with regards to cell-site location data, “the Fifth Circuit has not closed the door to anything that may be going on that we have not yet learned of,” he said.

Another critic of the NSA's phone collection program, Rep. Jason Chaffetz, R-Utah, has long been concerned with geolocation tracking and has also pushed intelligence officials to explain how they view their authority on gathering location data. During a House Judiciary Hearing in July, government officials assured Chaffetz that “we are not collecting that data, not under [section] 215” and that “we are not collecting that data under this program.” During the same exchange, Chaffetz pressed the witnesses on whether location data is considered metadata or whether it is protected under the Fourth Amendment. “This is an evolving area of the law,” Deputy Attorney General James Cole said in response.

A more accurate answer would be that location information is either constitutionally protected or not depending on how it is obtained. When it comes to cell-site tower information, that data is currently free for the taking.

Of course, section 215 is not the only source of the government's authority on location tracking. It is plausible, privacy advocates note, that if a bulk collection program exists for location data, it could be conducted under section 214, which expanded the government's authority to monitor communications electronically for foreign intelligence operations. “If there were any kind of location tracking -- whatever location tracking is done, is done, in my view, in my guess, outside of [section] 215,” said one privacy advocate who asked not to be named, but expressed skepticism that the government was lying about it's authorities under section 215 specifically.

“If you know who someone called, when they called, where they called from, and how long they talked, you lay bare the personal lives of law-abiding Americans to the scrutiny of government bureaucrats and outside contractors,” Wyden said in his speech last week. “This is particularly true if you’re vacuuming up cell phone location data, essentially turning every American’s cell phone into a tracking device.”