The Warrant Requirement and the Exclusionary Rule - Module 2 of 5
Module 2: The Warrant Requirement and the Exclusionary Rule
In Module 2, we will discuss the warrant requirement, probable cause, and the exclusionary rule. The first two of these requirements are specifically mentioned in the text of the Fourth Amendment. But all three of these principles play important and distinct parts in the realm of Fourth Amendment jurisprudence.
The Warrant Requirement
module, we discussed what constitutes a search or seizure. Once it is
determined that there is a search or seizure for Fourth Amendment purposes, the
next inquiry requires a determination regarding whether a warrant is necessary
and, if so, what it must contain. The Fourth Amendment provides that “no
Warrants shall issue, but upon probable cause, supported by Oath or
The Supreme Court has observed “the most basic constitutional rule in this area
is that searches conducted outside the judicial process, without prior approval
by judge or magistrate, are per se unreasonable under the Fourth Amendment.”
Of course, this does not mean that warrants are required for every search. There
are exceptions to the warrant requirement which we’ll focus on later in the
course. Still, those exceptions are narrow, and the assumption is that all
searches should be conducted pursuant to valid search warrants.
secure a valid warrant, an officer must seek out a detached magistrate or judge
and establish probable cause supported by an oath or affirmation. This is
usually done through an application for a warrant whereby the facts and
circumstances are laid out and the officer signs an affidavit to accompany the
application wherein the officer swears or affirms as to the factual basis of
the statements in the application. The magistrate or judge who makes the
determination regarding probable cause then considers all the statements in the
application to determine whether probable cause exists.
While warrants all need to conform to the Fourth Amendment’s minimal requirements, standards regarding the form and content of a warrant are usually established by local law or court rules. The Fourth Amendment provides that warrants must “particularly describe the place to be searched and the persons or things to be seized.” Courts disfavor over-broad and general warrants inasmuch as these are the types of warrants that the framers intended to prohibit when drafting the Fourth Amendment. Although minor mistakes do not necessarily invalidate warrants, the descriptions of the places to be searched and the persons or things to be seized must be sufficient to leave “nothing . . . to the discretion of the officer executing the warrant.”
cause, like “search or seizure,” is a phrase that is explicitly mentioned by
the Fourth Amendment. Probable cause is the standard that must be met for any
warrants to issue and for any searches or seizures to be executed. There are
two definitions of probable cause – the level of probable cause necessary for a
search and that necessary for an arrest.
start with the probable cause necessary to justify a search. Probable cause is
determined based on the totality-of-the-circumstances test, which means that
the court will consider all the factors present and known to the officer at the
time of the search or seizure.
cause to search exists when the facts and circumstances within the officers’
knowledge and of which they have reasonably trustworthy information are
sufficient in themselves to warrant a man of reasonable caution in the belief
that an item subject to seizure will be found in the place to be searched.
The search cannot be based on just a “hunch.”
an officer notices a car speeding down a residential road at 2:00 AM. After the
officer pulls the vehicle over, the officer notices that the driver has red and
glassy eyes. The officer orders the driver out of the car, searches the car,
and finds a large quantity of marijuana. A court, after considering the
totality of the circumstances, would likely hold that the facts known to the
officer at the time of the search did not rise to the level of probable cause
and the search was based on a hunch. As such, a court would likely conclude
such a search was illegal under the Fourth Amendment.
However, assume the
officer observes the car weaving back and forth on the street at 2:00 in the
morning. After pulling the car over, the officer approaches the driver’s side
window and notices the occupants are very nervous. The officer asks the driver
to lower the window and when the driver does, he notices a foggy substance coming
out which appears to be marijuana smoke. While speaking with the driver, the
officer notices a Ziploc bag of pills, a pipe and a bag with an unidentified
white powdery substance lying next to the front-seat passenger’s feet. It seems
clear that in this case there is probable cause to search the car.
However, it is
not always as simple as choosing between one of these scenarios. Facts can
range from clear and obvious to obscure and everything in between. Probable
cause to arrest is a separate analysis. It exists where the facts and circumstances within the officers’ knowledge and of
which they have reasonably trustworthy information are sufficient to warrant a
man of reasonable caution in the belief that an offense has been or is being
committed by the person arrested. There
must be facts to show that the person committed or is in the process of
committing a crime.
Going back to the officer who had probable cause to search the car, strong evidence of illegal drugs in the case is probable to arrest at least the driver and any occupant who apparently has possession of the illegal substances.
The Exclusionary Rule and Fruit of the Poisonous Tree
rule dictates that evidence seized illegally by a government agent is
inadmissible at trial. The rationale behind this rule is deterrence.
The idea is that if the evidence is excluded at trial it will force government
agents to follow the law and will deter them from violating the Fourth
exclusionary rule is a relatively new doctrine in American jurisprudence. Its
roots were in a 1914 case, Weeks v.
Because that case involved the federal government, for many years it was not
clear whether the exclusionary rule applied to the states. However, in 1961,
the Supreme Court decided Mapp v. Ohio,
extending the exclusionary rule to the states through the Due Process Clause of
the Fourteenth Amendment.
Thus, regardless of how incriminating the evidence is, evidence seized
illegally by law enforcement may not be used against any state or federal
once evidence is excluded, the fruit of
the poisonous tree rule requires that all evidence that was obtained
because of the illegally seized evidence is also inadmissible at trial. In Silverthorne Lumber Co., Inc. v. United
the Supreme Court explained that the Fourth Amendment prohibited the Government
from gaining any advantage through illegally-obtained evidence.
fruit of the poisonous tree rule can sometimes mandate harsh and even
incongruous results. Take, for example, the case of a police officer who
illegally searches a person’s trunk and finds cocaine. The officer arrests the
driver and, while conducting a search incident to the arrest, finds an illegal
handgun in his pocket that is later tied to a murder. He then gets a warrant
and searches the driver’s house, where he finds two dead bodies in the
basement, a stash of child porn on his computer and 12 kilograms of
methamphetamine behind the peanut butter in the kitchen pantry. After being
arrested, the suspect confesses to 3 murders, drug trafficking, running a child
prostitution ring and to being an all-around bad guy.
All this evidence would be excluded under the fruit of the poisonous tree rule, including the confession because none of this would have been obtained but for the illegal search of the trunk. It all grew from the poisoned tree of the initial illegal search. Unless the government can find other, clean evidence, this really, really, bad guy will walk.
Exceptions to the Exclusionary Rule
the years, the Supreme Court has carved out exceptions to the exclusionary and
fruit of the poisonous tree rules, largely to mitigate their harsh effects. In United States v. Leon,
the Supreme Court carved out a “good faith exception” to the exclusionary rule.
It allows the prosecution to use evidence obtained from an invalid warrant so
long as that warrant was executed by the police in good faith. Keep in mind
that the exclusionary rule is meant as a deterrent – to convince police
officers to respect the Fourth Amendment rights of suspects. You cannot deter
good faith mistakes. If the police acted based on what they thought was a valid
warrant, there would be no point in applying the exclusionary rule.
the “magistrate or judge in issuing a warrant was misled by information in an
affidavit that the affiant knew was false or would have known was false except
for his reckless disregard for the truth,” then suppression would be required.
In such case, there is no true “good faith.” Moreover, the
good faith exception applies only where police held a (supposedly) valid
warrant. If police make a warrantless search under what they believe is an
exception to the warrant requirement, or where police conduct a search and they
(honestly) believe that no warrant is required, there is no applicable
exception and the exclusionary rule must be applied.
Additionally, the Supreme Court has established the impeachment exception to the Exclusionary Rule. Even if evidence is excluded, if the defendant takes the stand in a criminal case and lies on the stand, the prosecution can admit the illegally obtained and excluded evidence to impeach the defendant. So, for example, if the police illegally seize the defendant’s cocaine and the defendant testifies that he’s never possessed cocaine in his life, the prosecution can introduce the seized cocaine to impeach that statement. However, it should be noted that this applies only to impeach the defendant, not to impeach other witnesses who may testify on the defendant’s behalf.
Exceptions to the Fruit of the Poisonous Tree Rule
illegally obtained evidence leads to the discovery of other evidence, the
fruits of the poisonous tree can still be admissible if there was an independent
source of that evidence. So, if, based on evidence found during an illegal
search, police find a trove of guns or narcotics, but police can show that another
witness had told, or was about to tell, police of the location of the same
trove, it is admissible. Here, the evidence would have been discovered even
without the illegal search and so it is not considered tainted evidence. 
next exception is the rule of attenuation, which allows a court to admit
otherwise inadmissible evidence when it is sufficiently separated from the
initial illegal discovery of the evidence. The idea is—somewhat similar to the
independent source doctrine—that the attenuation dissipates the illegal taint.
In Brown v. Illinois, the Supreme
Court laid out three factors which courts should consider when determining
whether the violation is sufficiently separated from the initial taint: (1) the
length of time between the illegality and the seizure of evidence; (2) the
presence of additional intervening factors; and (3) the degree and purpose of
the official misconduct.
an officer stops a person with no basis, constituting an unlawful seizure.
Following the stop, the officer runs the driver’s information. In the course of
this search, he pulls up an outstanding arrest warrant. The officer arrests the
person, searches him and finds a bag of cocaine, a wad of cash and a small
ledger with what looks to be customer information pertaining to drug sales.
the initial illegal stop, a court could find that the outstanding arrest
warrant attenuated the connection between the unlawful stop and the evidence
seized incident to arrest.
The court would consider the intervening factor of the outstanding warrant
(which was obviously not a product of police misconduct) and may also consider
whether the police officer originally made the stop with some colorable basis
to believe it was legitimate. If the initial stop was an honest mistake, the
court could conceivably rule that the illegal stop was far enough removed from
the ultimate search to avoid applying the fruit of the poisonous tree rule,
even though the stop was certainly the “but-for” cause of finding the cocaine.
another exception to the Exclusionary Rule is what is called the inevitable
discovery exception. The Court established the inevitable discovery
exception in 1984 in Nix v. Williams.
The inevitable discovery exception allows evidence to be used if the government
would have found the evidence regardless of the illegality.
an example, assume officers pulled over a defendant for driving under the
influence and placed him under arrest. Before taking the defendant to the
station, the officers illegally opened the trunk and found illegal guns. Although
the officers illegally opened the trunk, the officers were going to tow the
vehicle down to the station and perform an inventory search to secure the
defendant’s belongings anyway. As such, the guns would have been discovered in
short order even without the illegal search.
In the next Module, we will begin our discussion on the exceptions to the warrant requirement and where warrants are unnecessary for proper searches.
 John W. Hall, Jr., 5 Search and Seizure § 53.03 (LEXIS 2017).
 U.S. Const., amend IV.
 “Article: I. Investigations and Police Practices,” 43 Geo. L.J. Ann. Rev. Crim. Proc. 3, 31 (2014).
 Kit Kinports, “Probable Cause and Reasonable Suspicion:Totality Tests or Rigid Rules?” 163 U. Pa. L. Rev. 75, 75-76 (2014).
 Mapp v. Ohio, 367 U.S. 643, 655-56 (1961).
 Silverthorne Lumber Co., Inc. v. United States, 251 U.S. 385, 391-92(1920); Robert M. Pitler, “The Fruit ofthe Poisonous Tree Revisited and Shepardized,” 56 Cal. L. Rev. 579, 589 (1968).
 Silverthorne Lumber Co., 251 U.S. at 391-92.
 Id. at 923.
 Jeffrey M. Bain & Michael K. Kelly, “Fruit of the PoisonousTree: Recent Developments as Views Through Its Exceptions,” 31 U. Miami L. Rev. 615, 622-25 (1977).
 Heather A. Jackson, “Arizonav. Evans: Expanding Exclusionary RuleExceptions and Contracting Fourth Amendment Protection,” 86 J. Crim. L. & Crim. 1201, 1209 (1996).
 See id. at 443-44; Jackson, supra note 19, at 1206.