In the second, the Court extended this doctrine to hold that people are not entitled to Fourth Amendment safeguards for records given to a third-party or data generated as part of a person's business transactions with a third-party. In two of the most prominent third-party cases, Smith v. Maryland and United States v. Miller , the Court held that government access to telephone calling records and bank records, respectively, were not Fourth Amendment searches for which warrants were required. Both Smith and Miller , decided in the mid- to late-1970s, came before the mass digital revolution experienced over the last several decades. Since these decisions, there has been a wave of advancement in data generation, collection, automation, and processing. Two major events in the past few years typify this ongoing debate. The second is the litigation surrounding the National Security Agency's telephone metadata program. With these shifts in technology and legal thinking in mind, this report explores the history and legal foundations of the third-party doctrine. It will then analyze the Court's third-party doctrine cases and provide doctrinal and practical arguments for and against its application. Reasonable Expectation of Privacy and the Secrecy Model of Privacy

In 1967, the Court decided Katz v. United States , which abandoned the literal interpretation of the Fourth Amendment—one that protected only persons, houses, papers, and effects—to one that also protected intangible interests such as privacy. This would have significant consequences for government access to records and other information held by third parties. The Supreme Court disagreed, however, and upheld the surreptitious surveillance. With White , the Court combined several ideas in its Fourth Amendment jurisprudence: first, that it is unreasonable for people to expect privacy in information they share with another, and second, that they assume the risk that that information can be handed over to the government. Looking to both this assumption of the risk theory and the secrecy model, the Court then included the following sentence which would come to encapsulate the third-party doctrine:
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. In the 1877 case Ex p arte Jackson , the Supreme Court held that the content of a mailed letter was protected under the Fourth Amendment, while the information exposed to the public, such as the address written on the outside, was not. Further emphasizing this distinction, while Smith covered the telephone numbers a person dials to make a call, government access to the numbers dialed after a call has been placed, known as "post-cut through dialed digits," is considered a Fourth Amendment search. Criticism of the Third-Party Doctrine

While the third-party doctrine appears to fit reasonably well with the rest of Fourth Amendment case law, and has other weighty arguments in its favor, it has also had its share of vocal critics both on and off the Court. Implications of United States v. Jones on the Third-Party Doctrine

In addition to the doctrinal and practical arguments made against the third-party doctrine, several concurring opinions in the recent GPS tracking case United States v. Jones prompt additional questions about its continued application. As Justice Scalia's opinion relied upon a trespass theory of the Fourth Amendment, it will likely not have major repercussions for the third-party doctrine, unless one accepts that the government trespasses on an individual's "papers" or "effects" when it accesses records from third-party companies. However, two concurring opinions in Jones by Justices Sotomayor and Alito might signal the willingness of five Justices to reevaluate future applications of the third-party doctrine, at least with respect to pervasive government monitoring. She directly called into question "the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties." Other congressional measures would alter the third-party doctrine in a more targeted way.
In the 1970s, the Supreme Court handed down Smith v. Maryland and United States v. Miller, two of the most important Fourth Amendment decisions of the 20th century. In these cases, the Court held that people are not entitled to an expectation of privacy in information they voluntarily provide to third parties. This legal proposition, known as the third-party doctrine, permits the government access to, as a matter of Fourth Amendment law, a vast amount of information about individuals, such as the websites they visit; who they have emailed; the phone numbers they dial; and their utility, banking, and education records, just to name a few. Questions have been raised whether this doctrine is still viable in light of the major technological and social changes over the past several decades.
Before there were emails, instant messaging, and other forms of electronic communication, it was much easier for the courts to determine if a government investigation constituted a Fourth Amendment "search." If the police intruded on your person, house, papers, or effects—tangible property interests listed in the text of the Fourth Amendment—that act was considered a search, which had to be "reasonable" under the circumstances. However, with the advent of intangible forms of communication, like the telephone or the Internet, it became much more difficult for judges to determine when certain surveillance practices intruded upon Fourth Amendment rights. With Katz v. United States, the Court supposedly remedied this by declaring that the Fourth Amendment protects not only a person's tangible things, but additionally, his right to privacy. Katz, however, left unprotected anything a person knowingly exposes to the public. This idea would form the basis of Smith and Miller. In those cases, the Court held that a customer has no reasonable expectation of privacy in the phone numbers he dials (Smith) and in checks and deposit slips he gives to his bank (Miller), as he has exposed them to another and assumed the risk they could be handed over to the government.
While the third-party doctrine has been criticized by Members of Congress, various commentators, and others as overly constrictive of Americans' privacy rights, it appears to fit relatively well with other Fourth Amendment case law. That being said, advancements in data collection, automation, and use have some questioning the continued application of this doctrine in a digital society. Several events have precipitated renewed debates over its continued existence. First was the Supreme Court's decision in the GPS tracking case, United States v. Jones, where two concurring opinions comprising five Justices of the Court called into question various existing Fourth Amendment theories, including the third-party doctrine, at least with respect to long-term government monitoring and advanced surveillance technology. Second was the Edward Snowden leaks relating to the National Security Agency's telephone metadata program, which has been primarily justified by Smith and the third-party doctrine. Various Members of Congress have joined the debate, with some introducing legislation that would require a warrant for access to records held by third-parties, and others introducing more targeted measures that would limit access to information such as geolocation data from third-party companies.
With these legal, social, and technological trends in mind, this report explores the third party-doctrine, including its historical background, its legal and practical underpinnings, and its present and potential future applications. It explores the major third-party doctrine cases and fits them within the larger Fourth Amendment framework. It surveys the various doctrinal and practical arguments for and against its continued application. Lastly, this report describes congressional efforts to supplement legal protection for access to third-party records, as well as suggesting possible future directions in the law.