Applying the Fourth Amendment to the Internet: a general approach.

• Author: Kerr, Orin S.

INTRODUCTION I. THE FACTS OF PHYSICAL SPACE AND THE FACTS OF THE INTERNET A. The Inside/Outside Distinction 1. Outside and inside in physical investigations 2. Outside and inside in Internet investigations B. Physicality Limits Scale and Location 1. Physicality, scale, and the Fourth Amendment 2. Physicality and scale in Internet investigations C. The Assumption of Technology Neutrality II. REPLACING THE INSIDE/OUTSIDE DISTINCTION WITH THE CONTENT/NONCONTENT DISTINCTION A. The Content/Non-Content Distinction B. The Content/Non-Content Distinction as a Replacement for the Inside/Outside Distinction C. Existing Law on the Content/Non-Content Distinction 1. Postal letters 2. The telephone 3. Internet communications D. The Presumption that Contents of Communications Receive Fourth Amendment Protection E. Addressing Three Important Objections 1. The "Internet is different" argument 2. The incoherence argument 3. Reasonable expectations of privacy and the content/non-content line III. FOURTH AMENDMENT RULES FOR PROTECTED INTERNET DATA A. Applying the Warrant Requirement to Internet Communications B. The Unconstititionality of 18 U.S.C. [section] 2703(b) C. Particularity for Internet Communications CONCLUSION INTRODUCTION

The Internet has become an essential part of daily life for millions of Americans. Unfortunately, the many benefits of the Internet have been accompanied by increasing use of the Internet to commit crimes. Use of the Internet for criminal activity poses important new questions for the law of criminal investigations. How should the Fourth Amendment apply to the Internet? What kinds of online surveillance should the Constitution permit? When should the government be allowed to monitor a criminal suspect's email, web surfing, or instant messaging?

Courts have only recently begun to address these questions, and the existing legal scholarship is surprisingly sparse. (1) As the Ninth Circuit noted in a recent decision:

[T]he extent to which the Fourth Amendment provides protection for the contents of electronic communications in the Internet age is an open question. The recently minted standard of electronic communication via e-marls, text messages, and other means opens a new frontier in Fourth Amendment jurisprudence that has been little explored. (2) The existing scholarship tends to be either highly abstract (3) or else focuses only on discrete doctrinal questions. (4) A few scholars have pointed out that the application of the Fourth Amendment to computer networks will require considerable rethinking of preexisting law, (5) but none have sketched out what that rethinking might be.

This Article presents a general approach for how the Fourth Amendment should apply to Internet communications. It argues that the differences between the facts of physical space and the facts of the Interact require courts to identify new Fourth Amendment distinctions to maintain the function of Fourth Amendment rules in an online environment. It then recommends two key principles to guide the application of the Fourth Amendment to the Internet. This approach does not try to settle every question in every case. At the same time, it does provide the major guidelines that should frame how courts apply the Fourth Amendment to computer networks. These guidelines create a general framework for how to translate the constitutional protection against unreasonable searches and seizures to the Internet.

The method of this Article is premised on an assumption I call "technology neutrality." (6) Technology neutrality assumes that the degree of privacy the Fourth Amendment extends to the Internet should try to match the degree of privacy protection that the Fourth Amendment provides in the physical world. That is, courts should try to apply the Fourth Amendment in the new environment in ways that roughly replicate the role of the Fourth Amendment in the traditional physical setting. As a result, the goal of this Article is to map the protections of the Fourth Amendment from physical space to cyberspace. It attempts to accurately translate the physical distinctions of the Fourth Amendment to the new network environment. (7)

This Article makes two basic arguments about how the Fourth Amendment should apply to the Internet. The first argument is that the contents of online communications ordinarily should receive Fourth Amendment protection but that non-content information should not be protected. This approach accurately translates the traditional physical distinction between invasion into enclosed spaces and evidence collection in public. In a physical environment, the former is a Fourth Amendment search and the latter is not. Online, that role should be played by the distinction between the content of communications and noncontent information relating to those communications. Courts should hold that Internet users ordinarily have a reasonable expectation of privacy in the contents of the Internet communications but not in non-content information. Recent court decisions have pointed cautiously in this direction based on narrow analogies to the postal network and the telephone. (8) This article explains why the content/non-content distinction is not only justified by narrow analogies but also by its functional role and comparisons between the physical world and the Internet.

The second argument turns to what kinds of Fourth Amendment protection should apply once a court concludes that some Fourth Amendment protection is warranted. This Article argues that courts should apply a warrant requirement to Internet communications, but that the particularity requirement should permit warrants for individual suspects rather than individual Internet accounts. In other words, a warrant should ordinarily be required to access the contents of Internet communications. The federal statute that permits the government to compel contents with less process than a warrant in some cases is therefore unconstitutional in many applications. At the same time, when the government establishes probable cause to believe that a person has or will use the Internet to store, transmit, or receive specific evidence of criminal activity, any account that the person has or will use--and that therefore might plausibly contain the evidence sought--should be included within the scope of the warrant. Although statutory authorities may adopt a narrower approach, the constitutional particularity requirement should apply to Internet users instead of Internet accounts.

The broader goal of this Article is to imagine how the traditional rules of police investigations can translate into rules within the new environment of computer networks and computer crimes. It imagines a world in which individuals commit their crimes entirely over the Internet, and it considers how the Fourth Amendment might regulate the government investigations that will follow. It concludes that new facts will trigger the need for new rules to restore the traditional function of the law. By appreciating the differences between how physical and virtual spaces regulate human behavior, it becomes possible to see how the constitutional principles established for a traditional physical environment can apply to the new environment of computer networks.

This Article proceeds in three parts. Part I considers the factual differences between the physical world and the Internet that will require an adjustment of the traditional Fourth Amendment rules in the translation of the Fourth Amendment to the Internet. It also explains and justifies the assumption of technology neutrality. Part II argues that these differences will require replacing the inside/outside distinction in the physical world with the content/non-content distinction for Internet communications. Part III argues that the warrant requirement should nonetheless apply to Internet communications, but that the particularity requirement should allow searches through multiple accounts belonging to the same criminal suspect.

1. THE FACTS OF PHYSICAL SPACE AND THE FACTS OF THE INTERNET

   Technology provides new ways to do old things more easily, more cheaply, and more quickly than before. As technology advances, legal rules designed for one state of technology begin to take on unintended consequences. (9) If technological change results in an entirely new technological environment, the old rules no longer serve the same function. New rules may be needed to reestablish the function of the old rules in the new technological environment. (10)

   This Part will introduce two major factual differences between the physical world and the Internet that demand changes in how the Fourth Amendment will apply. The first difference is the elimination of the inside/outside distinction, and the second difference is the removal of physical limits on scale and locality. When paired with the assumption of technology neutrality, these differences require a translation of Fourth Amendment principles to the Internet through a rethinking of Fourth Amendment rules to ensure that the basic function of the Fourth Amendment is the same online as it is offline.

   1. The Inside/Outside Distinction

      The first important distinction between the facts of physical investigations and those of Internet investigations is the loss of the inside/outside distinction. In the physical world, the distinction between inside surveillance and outside surveillance is foundational. The law of police investigations naturally harnesses that line to distinguish between what the police can do without cause and what they need cause to do. Online, however, that same distinction no longer serves the purpose that it serves in physical world investigations. Applying the Fourth Amendment to the Internet must therefore begin by finding a new distinction to mirror the traditional physical distinction between inside and outside.

      1. Outside and inside in physical investigations

         The distinction between government...