Legal Aspects of Criminal
Investigation: Arrest, Search and
Detention vs. Arrest
 Detention: a temporary and limited interference
with the freedom of a person for investigative
 Arrest: interfering with the freedom of a person
who is suspected of criminal conduct to the extent of
taking him to the police station for some purpose
Essential Ingredients of an Arrest
 There are three essential ingredients:
 Intention: the officer must have the intention of taking the
suspect into custody
 Authority: the officer must have the actual authority to
make a legal arrest or at least believe this to be the case (ex:
an investigator makes an arrest under a defective warrant
but does not know about the defect)
 Custody: the person arrested must come within the custody
and control of the law
Situations in Which an Arrest is Permitted
 Warrant: a judicial order commanding the person
to whom it is issued to arrest a particular individual
and bring that person before a court to answer a
criminal charge
 Crime is committed in the presence of an
arresting officer
 Probable cause: it is suspicion plus facts and
circumstances that would lead a reasonable person
exercising ordinary caution to believe that a felony
crime has been, is being, or is about to be committed
Situations in Which an Arrest is Permitted (cont.)
 Statutorily created instances: by legislation,
states allow arrest in nonfelony cases even though
the offense is not committed in the officer’s
presence; examples are cases of domestic violence
and battery
Arrest Warrant
 In most cases, the warrant must be issued by a judge
who personally reviews the facts to determine the
existence of reasonable grounds
 The warrant must be supported by an affidavit, a
written statement of the information known to the
officer that serves as the basis for the issuance of the
Contents in the Warrant
 The authority under which the warrant is issued (the
name of the state)
The person who is to execute the warrant (generally
addressed to any peace officer of the state)
The identity of the person to be arrested
The designation of the offense
The date, time, and place of the occurrence
The name of the victim
A description of the offense and how it occurred
Example of a
Weeks vs. United States (1914)
 In this federal case, Weeks was charged with federal
crimes and evidence obtained without a search warrant
was used to convict him
On appeal, the Supreme Court ruled that the evidence
was not admissible and overturned the conviction
This became the basis for the federal exclusionary
rule; but the states had no such rule
State officers could obtain evidence illegally and hand it
over to federal agents; this became the “Silver Platter
In 1960, the Supreme Court prohibited the introduction
of all illegally seized evidence
Mapp v. Ohio (1961)
 In 1957, Cleveland police presented a “warrant” to
Ms. Mapp and searched her house
 Evidence was collected and Ms. Mapp was arrested
 At trial Ms. Mapp was convicted, even though the
search warrant was never produced
 Her case was appealed to the Supreme Court, who
decided in 1961 that any evidence unreasonably
searched and seized would no longer be admissible
in any court—state or federal
Search Warrant
 A written order, in the name of the state, that is
signed by a judicial officer exercising proper
 Directs a law enforcement officer to search for
specific property and bring it before the court
 Must be based on probable cause established by a
written affidavit prepared by the law enforcement
 Must describe the place to be searched and what is to
be seized
Warrantless Searches
 There are instances when searches can be conducted
without a warrant
 Search with Consent:
if an officer asks if he can search a person, vehicle, etc. and the
person says yes, the search may be conducted
if the person shares the space (i.e. a roommate in an
apartment), only the space of the person giving consent can be
consent must be voluntary (can’t be obtained through threats
or intimidation)
consent can be withdrawn at which point the search must stop
Warrantless Searches (cont.)
 Search Incident to Arrest:
 officers can search people who are being arrested
 these searches are to protect police officers and preserve
 the area under the immediate control of the person being
arrested can be searched to prevent the person from obtaining
a weapon or destroying evidence
 Search of a Motor Vehicle:
 if there is sufficient probable cause to get a warrant, but
because a vehicle is movable, the Supreme Court has ruled that
the car can be legally searched without a warrant
 when an officer makes a lawful arrest of the occupant of an
automobile, the passenger compartment can be searched (the
trunk cannot)
Warrantless Searches (cont.)
 Exigent Circumstances: recognizes a warrantless
entry by law enforcement officials when there is a
compelling need for official action or there is no time
to get a warrant (ex: danger of flight, loss or
destruction of evidence, risk of harm to the public or
police, and mobility of a vehicle)
 Conducting an Inventory:
law enforcement agencies have the obligation to inventory
property taken from an arrested person
the purpose is to protect the property of the arrested person
Plain View Seizure
 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
Stop and Frisk (Terry v. Ohio)
 In this Supreme Court case, the Court ruled that
under circumstances where a person is acting
suspiciously and the officer is concerned about his
own safety when approaching such an individual, the
officer may pat down the outer clothing to determine
if the person has a weapon even though there was no
 If a weapon is found, it may be seized and can be
used as evidence
 The officer can frisk for weapons only

Arrest, Search and Seizure