One of the most cherished yet misunderstood legal principles of American jurisprudence is the Fourth Amendment. Many people do not understand what their Fourth Amendment rights entail, when and how they can assert them and in what circumstances Fourth Amendment rights are being infringed. In this course, we’ll focus on explaining what these rights are, how they are enforced and their exceptions.
We’ll begin with a brief history of how we got here to understand the Fourth Amendment and the importance of this civil liberty. Search and arrest warrants find their origins in English common law. Search warrants, which can be traced back to as early as the sixteenth century, were considered “special” warrants. The victim of a crime had to go before a justice of the peace, testify under oath with particularity as to the crime (such as by describing the goods that were stolen and when and how they were stolen), and then the victim could go with the constable to recover the goods and bring the accused with the goods to a justice for disposition of the matter.
An arrest warrant was a command to the sheriff of a county or marshal of a court to apprehend a felon and bring him to court. Another category of warrants, and probably the most controversial, were writs of assistance. These writs were general warrants, which required no particularized showing of wrongdoing. These were absolute, unlimited and permanent warrants for customs officials to search at their discretion. Writs of assistance were primarily a means to combat smuggling, especially in the American colonies.
New writs of assistance that were requested in 1760 prompted a group of Boston merchants to oppose the proposed writs. These merchants retained James Otis to represent them. Otis argued that the Superior Court should not continue to grant the writs in general and open-ended form; rather, it should be limited to particularized suspicion based on the circumstances. Sitting in the audience and profusely taking notes was John Adams—one of the founding fathers of the United States Constitution. Although Otis and the Boston merchants lost the case, this became a major turning point for the American Revolution and ultimately the formulation of the Fourth Amendment.
The Fourth Amendment provides:
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.
A multitude of case law has developed over the last century to interpret this Amendment. The starting place for any Fourth Amendment analysis is determining whether there is government action. If there is government action, the next step is to determine whether the government intrusion rises to the level of a “search,” as not all government encounters are “searches and seizures” for Fourth Amendment purposes. If an action is not a search or seizure under the Fourth Amendment, no warrant is necessary, and no further analysis is needed.
Finally, if there is a government search or seizure, it must be determined whether probable cause existed for the government intrusion, as “probable cause” is required for warrants and as a condition of some of the exceptions to the warrant requirement.
When the Fourth Amendment Applies
A private person acting on her own behalf does not implicate the Fourth Amendment. Thus, the action of a private person searching through the personal belongings of somebody else, finding something illegal, and turning it over to the police is not a search under the Fourth Amendment. Similarly, a private person holding somebody against her will is not a seizure under the Fourth Amendment.
However, there are some exceptions to these rules. If these scenarios were changed and the private people were acting at the direction or even the suggestion of the police or a government agent, then these “intrusions” would be subject to the Fourth Amendment. The key factor is that there must be some level of action with, relationship with, or direction by, the government to subject a search or seizure to the Fourth Amendment.
The next issue is to define a “search or seizure.” The definition of what constitutes a search or seizure has transitioned over the past decades. Thus, it is important to go through a brief overview of how the Supreme Court has defined a “search or seizure” and its evolution over time.
In 1928, in Olmstead v. United States, the Court applied a very narrow definition of the term “search” when a majority allowed the government to use evidence from a police tap of a private phone line without a warrant. The Court ruled that a search or seizure implicated the Fourth Amendment only when the government intruded upon an area which was protected by the Constitution and the intrusion involved a physical invasion or trespass which was constitutionally impermissible. Over a vigorous dissent, the Court expressly declined to protect intercepted phone conversations by the government by making them inadmissible.
In 1967, however, the Court overruled Olmstead in Katz v. United States, which also dealt with a Fourth Amendment challenge to police tapping phone lines without a warrant, this time, a public phone booth that the defendant used. The Katz Court overruled Olmstead, ruling that the evidence stemming from the illegal recording was inadmissible. Still, the majority opinion written by Justice Stewart provided little guidance for courts to navigate Fourth Amendment cases. It was Justice Harlan’s concurrence that served as the model definition for courts to use for the more than 50 years since. Justice Harlan’s concurrence provided that the question depended on: (1) Did the person have an actual expectation of privacy in the activity; and (2) Was that expectation one that society would recognize as reasonable? This test is known as the “reasonable expectation of privacy” test.
There are many cases in which a defendant may have had a subjective expectation of privacy, but it was not an expectation that society would recognize as reasonable. Some examples of cases where there is no reasonable expectation of privacy include: aerial surveillance by police, since anyone can look down from an airplane; police searching garbage left out on the curb, since anyone or anything can rummage through it; and police using registers to track phone numbers that are dialed, since numbers are willingly disclosed to the phone company who is a third-party.
Defining a Search under United States v. Jones
In a 2012 case, United States v. Jones, the Supreme Court was confronted with the issue of whether the government, without a warrant, can track and monitor a vehicle by attaching a GPS tracker to it. The Court unanimously found that this was a search for the purposes of the Fourth Amendment and, as such, the government needed to obtain a warrant. The Justices were split as to what test to use. Four Justices believed that the Court should use the “reasonable expectation of privacy” test.
However, Justice Scalia, who wrote the majority opinion on behalf of the other five Justices, took the position that since the Fourth Amendment specifically mentions “persons, houses, papers, and effects,” there is a close and sacred connection between the Fourth Amendment and property. The majority discussed the history of the Fourth Amendment and how it was tied to common-law trespass until Katz. Therefore, the Jones Court declared that a crucial inquiry was whether the government intruded on an area which was protected by the property right of the defendant. If so, the Fourth Amendment may be violated even where there may not have been a reasonable expectation of privacy. While one may not have a reasonable expectation of privacy in the location of one’s car, the government cannot violate a property right by installing a GPS and then use the product of that property right violation as evidence against the defendant.
Thus, today, there are two tests that need to be analyzed to determine whether there is a search for Fourth Amendment purposes. First, you should look to the Jones Court test and ask if the search was of “persons, houses, papers, and effects.” If so, does the government action constitute a trespass of those property rights? If yes, there is a search or seizure that is subject to the Fourth Amendment. It not, it is still a search and seizure if the government infringed on the defendant’s reasonable expectation of privacy.
The Carpenter Case
Let’s look at an example to apply the Jones test. Imagine police, without a warrant, use cell phone towers to, in real time, track a person’s cell-phone location through the towers with which his mobile phone is communicating when he makes calls, sends or receives text messages or uses data.
Under the Jones test, we first ask if police violated the defendant’s property right. In this case, the answer is no, as officers were tracking movements through cell phone towers not owned by the defendant and there was no “physical intrusion” into the cell phone since police were only monitoring its location. So now we would have to turn to the reasonable-expectation-of-privacy test. Even assuming the defendant is very secretive and takes great pains to protect her known whereabouts, it is doubtful that it would be considered reasonable to expect one’s whereabouts to remain secret when one is using cell phone data. The ability to track movements using cell phone data is common knowledge and reasonable people should realize that their location can be tracked when operating a mobile device. As such, it would seem that there would be no Fourth Amendment “search.”
Still, in a 2018 case, United States v. Carpenter, the Court ruled that there IS a reasonable expectation of privacy regarding accessing historical cell phone location records from a user’s mobile service provider. The Court acknowledged that “personal location information maintained by a third party does not fit neatly under existing precedents,” but maintained that people have reasonable expectations of privacy in the “whole of their physical movements.” It compared the case to the Jones case involving the implant of a GPS device, observing that “historical cell-site records present even greater privacy concerns than the GPS monitoring considered in Jones: They give the Government near perfect surveillance and allow it to travel back in time to retrace a person’s whereabouts, subject only to the five-year retention policies of most wireless carriers.”
The Court did caution, however, that it did not mean to “call into question conventional surveillance techniques and tools, such as security cameras; does not address other business records that might incidentally reveal location information; and does not consider other collection techniques involving foreign affairs or national security.”
Note that in another case, the Sixth Circuit Court of Appeals ruled that “a subscriber enjoys a reasonable expectation of privacy in the contents of his emails ‘that are stored with, or sent or received through, a commercial ISP.’” Thus, “the government may not compel a commercial ISP to turn over the contents of a subscriber’s emails without first obtaining a warrant based on probable cause.”
In Module 2 we will discuss probable cause, which is the standard by which all searches under the Fourth Amendment are measured. We will also discuss the exclusionary rule and the mechanics of the warrant requirement.
 Thomas K. Clancy, The Framers’’ Intent: John Adams, His Era,and the Fourth Amendment, 86 Ind. L.J. 979, 990 (2011).
 Id. at 991.
 Id. at 991-92.
 Id. at 992.
 Id. at 996.
 See id. at 993.
 U.S. Const. amend. IV.
 See United States v. Jacobsen, 466 U.S. 109, 119 (1984); see also Sam Kamin, The Private Is Public: The Relevance of Private Actors in Defining the Fourth Amendment, 46 B.C.L. Rev. 83, 83 (2004).
 United States v. Soderstrand, 412 F.3d1146, 1153 (10th Cir. 2005); United States v. Souza, 223 F.3d 1197, 1201 (10th Cir. 2000).
 Olmstead v. United States, 277 U.S. 438, 466 (1928).
 Katz v. United States, 389 U.S. 347, 352-53 (1967).
 Colin Shaff, Is the Court Allergic to Katz? Problems Posed by New Methods ofElectronic Surveillance to the “Reasonable-Expectation-of Privacy” Test, 23 S. Cal. Interdisciplinary L.J. 409, 415 n.39 (2014).
 Katz, 389 U.S. at 361 (J., Harlan, concurring).
 California v. Ciraolo, 476 U.S. 207, 215 (1986).
 California v. Greenwood, 486 U.S. 35, 42 (1988).
Smith v. Maryland, 442 U.S. 735, 744-45 (1979).
 United States v. Jones, 132 S. Ct. 945, 949-51 (2012).
 Id. at 952.
 See id. at 949-53.
United States v.Carpenter, 138 S. Ct. 2206, 2217-19 (2018)
 Id. at 2210.
 United States v.Warshak, 631 F.3d 266, 288 (6th Cir. Dec. 2010)