More fundamentally, it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties. E.g., Smith, 442 U. S., at 742; United States v. Miller, 425 U. S. 435, 443 (1976) . This approach is ill suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks. People disclose the phone numbers that they dial or text to their cellular providers; the URLs that they visit and the e-mail addresses with which they correspond to their Internet service providers; and the books, groceries, and medications they purchase to online retailers.Justice Sotomayor in last year's U.S. v. Jones (GPS) ruling concurred separately to in effect agree with both halves of the justices' split, joining the majority while supporting the overall principle of the concurrence (Alito + the other liberals). She also questioned the so-called "third party" doctrine, noting the breadth of personal information that can be collected, including of a "familial, political, professional, religious, and sexual" nature. Such concerns were raised by various dissenting justices in the original cases. They continue to have force.
Jones involved placing a GPS device on a car, which was seen as a clear violation of the Fourth Amendment because it impinges on a property interest. See also, Florida v. Jardines, where dogs right outside one's home (the "curtilage" serving as a sort of "penumbras, formed by emanations" of the "houses" here) was also deemed an easy case. Three justices there noted a general concern for privacy also was implicated. This was the Alito approach earlier, though he was among the dissenters in Jardines, suggesting possible splits. Nonetheless, there are five votes there for a general privacy concern for long term monitoring of society.
The issue is now front and center with NSA tracking of what is called "metadata," which can tell a lot about someone, especially in the aggregate. This is seen in advertising -- a bunch of "cookies" regarding the websites you went to alone is pretty telling. If such data includes the headers of emails, it can be particularly informative. In the 1970s, pen registers, which provide numbers of whom you called was a concern to many people. After all, Smith v. Maryland was a 6-3 ruling (Stewart, Brennan and Marshall dissenting). An interesting discussion with a link to one involving a telling footnote can be found here (more here).
Alito's concurrence in Jones had a "I know it when I see it" test of sorts on how much monitoring is too much and was supportive of congressional regulation as a major means of dealing with the matter. It quotes Prof. Kerr, who has blogged about such issues at Volokh Conspiracy and wrote a lot about them as well. Kerr is very wary about Alito's approach as a judicial matter, critically speaking of a "mosaic theory" that in effect determines the government's surveillance as a whole is unreasonable. Seems too inexact to him, apparently. His overall 4A views are complex though.
At some point, I think such a theory makes sense as a Fourth Amendment matter, and the separate opinions in Jones suggest why as does. And, the theory was left open by past cases. As the majority in Jones noted,
reserved the question whether “different constitutional principles may be applicable” to “dragnet-type law enforcement practices[.]”The GPS tracked public movements of the car, but the breadth of the movements is on some level a difference in kind from merely having a police officer follow the car around. Four justices would apparently merely rely on that fact that the device invaded the "effect" -- the property interest a person has in the car. Unsure if Roberts and Kennedy, at least, would be that formalistic if pressed. Anyway, five justices didn't merely (Sotomayor) rely (Alito + three) on that. The monitoring infringes on the privacy of the user of the vehicle and the Fourth Amendment (and other possible amendments, especially the First, if we take Sotomayor's counsel) instructs that at some point this is "unreasonable" ... at least without a warrant. Two judges recently split on applying this to the NSA policy.
[ETA: Note that this is not just a matter of "Smith no longer being good law," which a lower court judge cannot say unless the USSC clearly so held -- the "clearly" has less force in certain cases if it turns out the USSC supports what the judges do. It is also that whatever the legitimacy of certain limited usage of "third party" material, a "dragnet-type" approach was not decided by past cases. One judge noted various possible differences -- distinguishing v. overruling is something of an art anyway.]
I would withhold my opinion on the specific proper route here, including if the NSA policy is unconstitutional. One thing that I'm sure about though is that it is appreciated that FINALLY it might be the case that there is clear standing to at least allow the federal courts (outside of FISA perhaps) to at least decide the question. I think the Obama Administration at times have gotten a bad rap as to the breadth of their wrongness on national security issues, but its refusal to allow various things even to be decided has rightly been deemed dead wrong. I understand the CYA behavior, so am not "shocked' about it all, but still find it dead wrong.
Also, the privacy concerns are appropriate -- the devil is in the details of how to handle them. There are various legislative safeguards here, even the rubber stamp nature of the FISA Court has been shown to be a bit exaggerated. There can be more. The particulars also matter a lot -- the NSA running computer programs 24/7 is "dragnet-type" but not very individualized. Specific attempts to use similar tactics to target specific people, such as in a specific drug or financial investigation can be a different case. What is clear is that merely because somehow we give the data to third parties (often only because of the necessities of life, like phone numbers, and with the belief it will be held privately by the company and not shared with others) shouldn't be enough to remove privacy concerns when the government without our permission monitors it and pressures communication companies to help them. That is a bit absurd and at best should be cabined.
Also, the level of data is way more than a few telephone numbers. Note that footnote discussed in the link above. Justice Stevens wanted to deal with reliance on expectation of privacy when some crazy totalitarian scenario becomes the expectation -- where we are "conditioned" to accept something out of 1984 or Fahrenheit 451 (the movie had wall video that directly talked to occupants) of "continuously monitoring" of everyone. Usage of a case where specific phones are monitored for numbers called or specific bank records are subpoenaed to justify this doesn't do it.