Police and the Constitution: The
Rules of Law Enforcement
The Fourth Amendment
The fourth amendment contains two critical
legal concepts:
 Unreasonable searches and seizures
 The requirement of probable cause to issue a
warrant
The Fourth Amendment
Sources of Probable Cause:
 Personal observation
 Information
 Evidence
 Association
The Fourth Amendment
The Exclusionary Rule:
 Prohibits the use of illegally obtained
evidence in court
The Fruit of the Poisoned Tree:
 Evidence obtained through illegally obtained
evidence is also inadmissable
The Fourth Amendment
Exceptions to the exclusionary rule:
 Inevitable discovery
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Brewer v. Williams (1977)
Nix v. Williams (1984)
Good Faith
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United States v. Leon (1984)
Stops and Frisks
A stop is the brief detention of a person by
the police for questioning. A stop requires
reasonable suspicion.
A frisk is a pat-down or minimal search by
police to discover weapons. It is conducted
for the protection of the officer.
Stops and Frisks
Stops and Frisks are governed by:
 Reasonable suspicion
 Terry v. Ohio (1968)
 The “totality of the circumstances”
Arrests
The elements of arrest:
 The intent to arrest
 The authority to arrest
 Seizure or detention
 The understanding of a person that they have
been arrested
Arrests
Arrests with a warrant:
 Officers are required to knock and announce
their presence. Wilson v. Arkansas (1967).
 Under certain exigent circumstances officers
do not need to announce themselves:
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The suspect is armed and dangerous.
Evidence is being destroyed.
A felony is in progress.
Arrests
Arrests without a warrant:
 The arrest is committed in the presence of the
officer; or
 The officer has knowledge a crime was
committed and probable cause to believe the
crime was committed by a particular person.
Lawful Search and Seizure
The role of privacy in searches:
 Katz v. United States (1967)
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A person must show they have an expectation of
privacy
That expectation must be reasonable
Greenwood v. California (1988)
Lawful Search and Seizure
Search warrants must demonstrate:
 Information showing probable cause that a
crime has been or will be committed.
 Specific information on the premises to be
searched, the suspects to be found and the
items to be seized.
Lawful Search and Seizure
Four categories of items that can be seized
by use of a search warrant:
 Items that resulted from a crime
 Items that are inherently illegal for anyone to
possess
 Items that can be called “evidence” of a crime
 Items used in committing the crime
Lawful Search and Seizure
Searches without a warrant:
 Searches incidental to arrest

United States v. Robinson (1973)
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The officer’s need to confiscate any weapons the
suspect may be carrying
The need to protect any evidence on the suspect’s
person from being destroyed
Chimel v. California (1969)
Lawful Search and Seizure
Searches without a warrant:
 Searches with consent
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Schneckcloth v. Bustamonte (1973)
Florida v. Bostick (1991)
Searches of automobiles
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The Carroll Doctrine
Whren v. United States (1996)
Maryland v. Wilson (1997)
Lawful Search and Seizure
Searches without a warrant:
 Plain view doctrine
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New Hampshire v. Coolidge (1971)
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The item is positioned in the officer’s view
The officer is legally in a position to notice the item
The discovery of the item is inadvertent
The officer immediately recognizes the illegal nature
of the item
Lawful Search and Seizure
Electronic surveillance can only be used:
 If consent is given by one of the parties
 Or there is a warrant authorizing the activity
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Names the persons under surveillance
Details the conversations to be recorded
Shows probable cause that a crime has been
committed
Lawful Search and Seizure
Electronic surveillance and national security:
 The USA PATRIOT Act of 2001
 The “sneak and peak” provision
 National Security Letters
The Interrogation Process and Miranda
Miranda is required:
 When a suspect is under arrest
 And is being questioned about an ongoing
investigation
This is called custodial interrogation.
The Interrogation Process and Miranda
The legal basis for Miranda:
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The Fifth Amendment protection against selfincrimination.
The Sixth Amendment right to counsel.
Escobedo v. Illinois (1964)
Miranda v. Arizona (1966)
The Interrogation Process and Miranda
Miranda is not required:
 When police do not ask suspect questions that are testimonial
in nature
 When the police have not focused on a suspect and are
questioning witnesses at the scene
 When a person volunteers information before being asked
 When the suspect has given a private statement
 During a stop and frisk when no arrest has been made
 During a traffic stop
The Interrogation Process and Miranda
Waivers of Miranda must be knowing and
voluntary.
To be clear, officers should ask:
 Do you understand your rights as I have read them to
you?
 Knowing these rights, are you willing to another law
enforcement officer or to me?