On Tuesday, the Foreign Intelligence Surveillance Court (FISC) declassified an opinion in which it explained why the government's collection of records of all Americans' phone calls is constitutional, and that if there is a problem with the program, it is a matter of political judgment, not constitutional law. So, should Americans just keep calm and carry on phoning? Not really.

Instead, we should worry about a court that, lacking a real adversarial process to inform it, failed while taking its best shot at explaining its position to the public to address the most basic, widely-known counter-argument to its position. The opinion does not even mention last year's unanimous US supreme court decision on the fourth amendment and GPS tracking, a decision in which all three opinions include strong language that may render the NSA's phone records collection program unconstitutional. No court that had been briefed by both sides would have ignored the grave constitutional issues raised by the three opinions of Justices Scalia, Sotomayor, and Alito in United States v Jones. And no opinion that fails to consider these should calm anyone down.

The newly-released FISC opinion, the first to opine on the legality of the phone metadata collection program since the Snowden leaks brought the program to national attention, is based on two straightforward points.

First, in 1979, the supreme court held in Smith v Maryland that using "pen registers" that record what number called what other number, when, and for how long, did not violate the fourth amendment. The court in Smith reasoned that individuals have no expectation of privacy in information they knowingly hand over to the phone company. The FISC reasoned that even though the NSA metadata program collected more information than the program the supreme court upheld 35 years ago, the details did not make a constitutional difference. Individuals have no fourth amendment rights in their phone call metadata.

The second component of the FISC argument was that "grouping together a large number of individuals", no single one of whom has "a fourth amendment interest", "cannot result in a fourth amendment interest springing into existence ex nihilo". Adding up many zeros doesn't create a positive value; bulk collection of unprotected materials over a sustained period of years raises no special constitutional considerations.

Standing on its own, this logic may seem persuasive. But only until you think about how last year's Jones decision by the supreme court destabilizes this logic.

In Jones, the government attached a GPS device to a suspect's car and tracked all the car's movements for four weeks. The government argued that since the car was visible on public roads, and could have been tracked in the open by a police officer, no warrant was needed. Just like phone metadata, the car's movements were not in private – they were on public roads. The lower court had already excluded evidence from when the car was parked in its private parking lot. All nine justices found the tracking unconstitutional, and each of the opinions offer strong reasons to reject the Fisa court's interpretation of the fourth amendment with regards to phone metadata.

Writing for the court, Scalia joined by three of the other conservatives and Sotomayor, would have decided the case based on the fact that attaching the GPS to the car was a kind of trespass, which was enough to trigger a fourth amendment interest. This primary opinion, standing alone, would have been easy to distinguish from the metadata collection because there is no trespass involved in the NSA program. But even Justice Scalia's narrow opinion quotes approvingly an earlier decision that "different constitutional principles may be applicable to dragnet-type law enforcement practices of the type that GPS tracking made possible here." Because there was no lawyer in front of it to push the issue, the FISC opinion didn't even try to explain why Scalia's statement did not flatly contradict the second premise of its logic.

Alito, joined by three of the liberals, argued that Scalia's approach was antiquated. Instead, he wrote that pervasive networked computation eroded "the greatest protections of privacy": the sheer difficulty and cost of maintaining long-term pervasive surveillance. Faced with dramatic changes in the technical capabilities of the state, Alito argued that legal constraints must be mounted to "assure preservation of that degree of privacy against government that existed when the fourth amendment was adopted".

The most sophisticated opinion about how "big data" changes what courts must do to protect against state surveillance was authored by Sotomayor, who also provided the fifth vote for the court's main opinion. Responding specifically to the claim that GPS tracking involved only non-private information from public travel, Sotomayor wrote that with today's technology even observing these purely public movements "generates a precise, comprehensive record of a person's public movements that reflect a wealth of detail about her familial, political, professional, religious and sexual associations".

As though writing about the NSA program itself, Sotomayor continued:

Awareness that the government may be watching chills associational and expressive freedoms. And the government's unrestrained power to assemble data that reveal private aspects of identity is susceptible to abuse.

A technology, she went on, that "mak[es] available at a relatively low cost such a substantial quantum of intimate information about any person whom the government, in its unfettered discretion, chooses to track may alter the relationship between citizen and government in a way that is inimical to democratic society". Indeed, Sotomayor explicitly noted that the Smith ruling itself may need to be revisited, given these changes.

The Jones decision does not necessarily determine that the NSA metadata collection program is unconstitutional. Good lawyers can make excellent arguments about its implications for various aspects of the NSA surveillance programs, and argue both sides. Reading the tea leaves of how this supreme court would decide this case when directly confronting phone call metadata as the tracking activity, with national security as the interest, is difficult at best.

But there is no question that all three Jones opinions offer a very strong argument that the dramatically lower cost of pervasive, sustained surveillance of publicly observable data in bulk implicates the fourth amendment, and that whatever its statutory basis, this program may well violate that amendment. That the FISC opinion did not even mention Jones is as clear a sign as we have that without fundamental reform, Americans simply cannot rely on the Fisa court's lopsided process to protect our rights.