134 Chapter 4Chapter 4 || Civil LibertiesCivil Libertiestheir mouths for royal inspection.”^118 Scalia argued that DNA evidence could be used to
identify the arrestee as a suspect in an unrelated crime and therefore a swab should be
taken only if there is probable cause that another crime has also been committed.
The Court has generally made it easier for law-enforcement officials to conduct
searches without warrants, but two important decisions in the other direction were a
2014 case that required a warrant to search cell phones of people who had been arrested^119
and a 2012 case that required a warrant to place a GPS tracking device on a vehicle. In
the latter case, the FBI suspected Antoine Jones of selling cocaine, so agents placed a
tracking device on his vehicle without a warrant, monitored his movements for four
weeks, and then used the evidence to convict him. Jones was sentenced to life in prison.
While the Court required a warrant in this specific case, the basis for the majority’s
decision was fairly narrow: the placement of the device was a “physical trespass,” and the
lengthy monitoring of his movement constituted an illegal search.^120 The Court provided
additional protection for privacy in 2018 when it ruled that a search warrant is required to
access cell phone location records. While the ruling made exceptions for emergencies such
as “bomb threats, active shootings, and child abductions,” the four dissenting justices
feared that law-enforcement officials were losing an important tool in fighting crime.^121The Exclusionary Rule Another important concern related to the Fourth Amendment
is what to do if the police obtain evidence illegally. Here the need to balance security
and privacy becomes concrete. Either the evidence is excluded from a criminal trial to
protect privacy rights or it is allowed to support the conviction of the suspect. In 1961,
the Fourth Amendment was incorporated (applied to the states through the Fourteenth
Amendment) in a case, Mapp v. Ohio. This case established for all courts the exclusionary
rule, which says that illegally or unconstitutionally obtained evidence cannot be used in a
criminal trial. Previously, the rule had applied only at the national level.^122
In the landmark case, police broke into Dollree Mapp’s residence without a warrant,
looking for a suspect thought to be hiding in the house. The officers did not find him, but
they did find illegal pornographic material, and Mapp was convicted of possessing it.
Mapp’s lawyer tried to defend her on First Amendment grounds, claiming she had the
right to own the pornography, but instead the Court used the opportunity to apply the
Fourth Amendment to the states. The Court threw out Mapp’s conviction because the
police did not have a search warrant, arguing that applying the Fourth Amendment only
to the national government and not to the states didn’t make any sense: Why should
a state’s attorney be able to use illegally obtained evidence while a federal prosecutor
could not? The justices ruled that for the exclusionary rule to deter illegal searches and
seizures, it must apply to law enforcement at both state and national levels.
Subsequently, the Supreme Court began weakening the exclusionary rule. For
example, the Court established a “good faith exception” to the exclusionary rule,
allowing evidence to be used as long as the officer believed that he or she had conducted
a legal search. In this specific case, the officer had a warrant with the wrong address.^123
Yet another case established an “independent source” exception allowing the use of
evidence that was initially obtained in an illegal search but subsequently acquired with
a valid warrant. A major new exception was established in 2016 when the Court ruled
that drugs found during a search in which an officer stopped a person with no probable
cause are admissible as evidence if there was an outstanding arrest warrant for the
suspect (in this case for a traffic offense) at the time of the search. Justice Sotomayor
pointed out in her dissent that there are 7.8 million outstanding warrants, mostly for
traffic and parking violations, which means that this new exception has far-reaching
consequences: “The mere existence of a warrant not only gives an officer legal cause
to arrest and search a person, it also forgives an officer who, with no knowledge of the
warrant at all, unlawfully stops that person on a whim or hunch.”^124 The bottom line isexclusionary rule
The principle that illegally or
unconstitutionally acquired evidence
cannot be used in a criminal trial.Can the police search your home
without a warrant? After Dollree
Mapp was arrested for possession of
pornographic material, the case made
its way to the Supreme Court and the
search was ruled unconstitutional.
This case established the exclusionary
rule for evidence that is obtained
without a warrant.Full_05_APT_64431_ch04_102-147.indd 134 16/11/18 1:31 PM