Chapter 2: Legal Aspects of Investigation
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Chapter 2
Legal Aspects of Investigation
Learning Objectives
1. Explain the historical evolution of the laws of arrest and search and seizure from the Bill of
Rights through the Fourteenth Amendment.
2. Describe and diagram the flow of constitutional rights to a defendant in a federal criminal
trial and a defendant in a state criminal trial.
3. Outline the requirements of a valid arrest warrant.
4. Describe whether a “John Doe” arrest warrant is ever valid, and if so, under what
circumstances.
Introduction
All law enforcement officers, uniformed and plainclothes, conduct investigations. That is a
statement of fact. There are, of course, differing concentrations of the investigative process and
varying responsibilities among different units and different people.
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Criminal law is divided into two major components that are interrelated yet serve different
functions. The substantive criminal law deals with those elements that describe and define a
crime. When an investigator has the needed proof to satisfy the particular elements of an offense,
it can then be said that the crime did occur.
The other component of criminal law is procedural criminal law. It is not enough to know
whether a crime has been committed. The investigator must understand what and how things
need to be done with the people involved in an investigation, be it a victim, a witness, an
informant, or a suspect. Thus, the procedural part of criminal law defines what can and cannot be
Lecture Notes
I. The Bill of Rights and the States
An examination of constitutional history reveals that the powers yielded by the states were
specifically granted for the purpose of establishing a national government. However, final
ratification of the new constitution was delayed because some states wanted guarantees that
Police agencies must disclose to the prosecution, who must disclose to the defense, any
exculpatory or impeachment evidence that demonstrates that a witness is lying about specific
facts in a case or is generally unworthy of belief, including the credibility of individual police
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officers and/or investigators. Evidence of this nature is often referred to as “Brady material.”
Failing to disclose such evidence is a Brady violation that can lead to dismissal of the criminal
case and civil (U.S. Code 42, Section 1983) cases brought against the individual prosecutor, the
police department, and the officer for violation of the suspect’s constitutional rights.
A. Evolution of the Fourteenth Amendment
The Civil War was over. Slavery had been abolished. The Thirteenth, Fourteenth, and
B. The Fourth Amendment
In part, the Fourth Amendment reads:
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
II. Arrest
There are a number of definitions of the term arrest. They range from “any interference with a
person which, if not privileged, would constitute false imprisonment,” to “interfering with the
A. Ingredients of Arrest
There are three essential ingredients of an arrest:
• Intention
B. Arrest Distinguished from Detention
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Detention is a temporary and limited interference with the freedom of a person for
investigative purposes. Sometimes called investigative detention, it is also commonly referred
C. Arrest Distinguished from Charging
Formally charging a suspect with a crime does not automatically flow from an arrest.
Charging follows a decision to prosecute.
D. Arrest Procedures
The laws of most jurisdictions permit an arrest in at least three and sometimes four types of
situations:
• When a warrant has been issued.
E. The Arrest Warrant
The preferred method of effecting an arrest is under the authority of a warrant. An arrest
warrant is a judicial order commanding the person to whom it is issued or some other person
F. Crime Committed in Presence
Any offense committed in the presence of an officer, whether felony or misdemeanor, can be
the basis of an arrest without a warrant.
G. Probable Cause
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The third major category in which a lawful arrest is generally permitted involves offenses not
committed in the officer’s presence and for which a warrant has not been issued. One
acceptable definition of probable cause is that it is more than suspicion but less than actual
III. Search and Seizure
The evolution of the law of search and seizure illustrates the relationship described earlier
between federal and state court systems and between the Bill of Rights and its application to the
states through the due process clause of the Fourteenth Amendment.
A. Legal Searches and Seizures
As is true for arrests, the Fourth Amendment also recognizes searches and seizures only by
B. Search with a Warrant
A search warrant is a written order, in the name of the state, signed by a judicial officer,
C. Search with Consent
One of the most common situations arising today is when a uniformed officer, in encountering
a citizen during a traffic stop or other routine activity, asks the person if he/she has any
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If the person denies consent, which he/she has the right to do, no search may be made unless
there is probable cause to conduct a search under one of the other exceptions to the warrant
requirement. A refusal to allow a search, standing alone, does not constitute probable cause to
justify any further action.
D. Search Incident to Arrest
The courts have regularly recognized the right of law enforcement officers to search people
who have been arrested without a warrant. Such searches are justified for officer safety and to
preserve evidence.
E. Search of a Motor Vehicle
The search of a motor vehicle, sometimes referred to as the automobile exception to the
requirement that a search be conducted with a warrant, really involves two distinct legal
The second issue involves the search of a vehicle incident to a lawful arrest. Keeping in mind
the foundation principle of the Chimel case, that a search may be made of the area under the
arrestee’s immediate control, the Supreme Court ruled in the 1981 case of New York v. Belton
F. Emergency (Exigent Circumstances)
The exigent circumstances exception recognizes that a warrantless entry by law enforcement
officials may be legal when there is a compelling need for official action and no time to get a
warrant. The exception covers several common situations including: danger of flight or
escape, loss or destruction of evidence, risk of harm to the public or police, mobility of a
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vehicle, and hot pursuit.
G. Conducting an Inventory
Law enforcement agencies have not only the right but also the obligation to inventory
H. Plain View Seizures
If an investigator/officer is lawfully in a place and sees contraband or evidence in plain view,
the investigator may seize the evidence and it will be admissible.
I. Stop and Frisk
Earlier in this chapter, the stop-and-frisk topic was mentioned to distinguish arrest from
detention. There is, of course, a search and seizure aspect to this concept.
J. Fruits of the Poisonous Tree
A final point is necessary to fully comprehend the consequences of an unreasonable search
and seizure. The fruits of the poisonous tree doctrine provides that evidence obtained from an