The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.People all over the internet are frequently making the assumption that the NSA's collection of metadata on telephone calls violates this amendment. As the recently released DOJ white paper on that program states, the Supreme Court has ruled repeatedly against that claim.
A Section 215 order for the production of telephony metadata is not a “search” as to any individual because, as the Supreme Court has expressly held, participants in telephone calls lack any reasonable expectation of privacy under the Fourth Amendment in the telephone numbers dialed. In Smith v. Maryland, 442 U.S. 735 (1979), the Supreme Court held that the Government’s collection of dialed telephone numbers from a telephone company did not constitute a search of the petitioner under the Fourth Amendment, because persons making phone calls lack a reasonable expectation of privacy in the numbers they call. Id. at 743-46. Even if a subscriber subjectively intends to keep the numbers dialed secret, the Court held, “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties.” Id. at 743-44. The Court explained that someone who uses a phone has “voluntarily conveyed numerical information to the telephone company and ‘exposed’ that information to its equipment in the ordinary course of business,” and therefore has “assumed the risk that the company would reveal to the police the numbers  dialed.” Id. at 744.As we know, for NSA to go beyond the collection of this metadata to view content requires multiple layers of safeguards including the acquisition of a warrant.
Although the telephony metadata obtained through Section 215 includes, in addition to the numbers dialed, the length and time of the calls and other similar dialing, routing, addressing, or signaling information, under the reasoning adopted by the Supreme Court in Smith, there is no reasonable expectation of privacy in such information, which is routinely collected by telecommunications service providers for billing and fraud detection purposes. Under longstanding Supreme Court precedent, this conclusion holds even if there is an understanding that the third party will treat the information as confidential. See, e.g., SEC v. Jerry T. O’Brien, Inc., 467 U.S. 735, 743 (1984); United States v. Miller, 425 U.S. 435, 443 (1976) (“This Court has held repeatedly that the Fourth Amendment does not prohibit the obtaining of information revealed to a third party and conveyed by him to Government authorities, even if the information is revealed on the assumption that it will be used only for a limited purpose and the confidence placed in the third party will not be betrayed.”)
Whether people think it is effective or prudent for the government to collect this information is a reasonable question to ask. But according to years of Supreme Court legal precedent, it is clearly not in violation of the Fourth Amendment.