Inside Criminal Law
Written Sources of American Criminal
Law
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American criminal law is codified, or written
down and accessible to all.
This allows citizens to know which acts are
illegal, and to understand the procedures used
to determine an individual’s innocence or
guilt.
Written sources of law are known as
substantive law.
Written Sources of American Criminal
Law

The U.S. Constitution
and the various state
constitutions

Statutes (or laws) and
ordinances passed by
Congress and state
legislatures
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Regulations, created by
agencies such as the
federal Food and Drug
Administration
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Case law (court
decisions)
The Purposes of Criminal Law
Protect and Punish: the legal function of the law
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Maintain social order by protecting citizens from
criminal harm
Includes harms to both individuals and society in
general
Maintain and Teach: the social function of the law
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Expressing public morality
Teaching social boundaries
The Elements of a Crime
Criminal law normally requires that the corpus
delicti (the body of the crime) be proved
before a person can be convicted of
wrongdoing
The Elements of a Crime
Corpus delicti consists of:

Criminal Act - Actus reus
Crimes may be acts of commission, or acts of omission,
or even attempted acts.
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Mental State - Mens rea
Intent is required to establish guilt of a crime. Intent
includes elements of purpose, knowledge, negligence, and
recklessness.
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Concurrance - The guilty act and the guilty intent must
occur together.
The Elements of a Crime
Mens Rea plays a crucial role in differentiating
between varying degrees of criminal
responsibility or criminal liability.
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Strict Liability – offenses hold the defendant guilty even
if intent to commit the offense is lacking
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Accomplice Liability – Suspects can be charged for
crimes they did not actually commit if it can be proven
they acted as an accomplice
The Elements of a Crime
Corpus delicti also consists of:
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Causation - The criminal act caused the harm suffered.
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Attendant Circumstances – In certain crimes,
accompanying circumstances are relevant to corpus delicti.
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Harm – Damages resultant from the criminal act.
Inchoate offenses are conduct deemed criminal without
actual harm being done.
Defenses Under Criminal Law
Excuse Defenses:
These defenses apply
When the actor lacks
the requisite mental
condition to form intent.
There are four excuse
defenses.
Justification Defenses:
These defenses apply
when the defendant
admits to the criminal
act, but argues that the
act was justified.
There are four
justification defenses.
Defenses Under Criminal Law
Excuse Defenses:
 Infancy - Youthful offenders cannot understand
the consequences of their actions.
 Insanity- A person cannot have the state of mind
(intent) to commit the crime if s/he didn’t know
the act was wrong, or didn’t understand the
quality of the act.
Defenses Under Criminal Law
Insanity is determined by:
 M’Naughten Rule
 A person is insane if they can’t distinguish right from
wrong
 ALI/MPC Test
 Also known as the substantial capacity test, the defendant
must lack the capacity to appreciate the wrongfulness of
his/her conduct.
 Irresistible Impulse Test
 A person is insane if some “irresistible impulse” resulting
from a mental deficiency drove him or her to commit the
crime
Defenses Under Criminal Law
Excuse Defenses:
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Intoxication
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Voluntary and Involuntary
Mistake
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Mistake of Fact
Mistake of Law
Defenses Under Criminal Law
Justification Defenses:
 Duress
 The defendant is threatened with seriously bodily
harm, which induces him/her to commit the crime.
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Self-Defense
 The defendant must protect him/herself from injury by
another.
 Duty to retreat? “Castle Doctrine” no duty to retreat if
in your home.
Defenses Under Criminal Law
Justification Defenses:
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Necessity
 Circumstances required the defendant to commit the
act.
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Entrapment
 The defendant claims s/he was induced by police to
commit the act. (Predisposed to commit the crime?)
Procedural Safeguards
Substantive Criminal Law:
Procedural Criminal
Law:
Law that defines the acts
that the government will
punish.
Procedures, drawn
from the Bill of
Rights, that are
designed to protect
the constitutional
rights of individuals.
Procedural Safeguards
The Bill of Rights:
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The first ten amendments to the U.S. Constitution are
known as the Bill of Rights.
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The Bill of Rights was adopted by the states in 1791.
Since then, seventeen more amendments have been added
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The Bill of Rights has served as the basis for procedural
safeguards of the accused in the U.S.
Procedural Safeguards
Procedural safeguards in the U.S. Constitution include:
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Fourth Amendment
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provides protection from unreasonable searches and seizures
Fifth Amendment
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requires that no one can be deprived of life, liberty, or property
without “due process of the law,” including protections against
double jeopardy and individuals being required to be a witness
against himself or herself
Procedural Safeguards
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Sixth Amendment
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Eighth Amendment
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guarantees a speedy trial, a trial by jury, a public trial, the right to
confront witnesses, and the right to a lawyer at various stages of
criminal proceedings
prohibits excessive bails, fines, and cruel and unusual
punishments
Fourteenth Amendment
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provides due process and equal protection of the laws
Procedural Safeguards
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Procedural due process
is a provision in the
Constitution that states
that the law must be
carried out in a fair and
orderly manner
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Substantive due
process is a
Constitutional
requirement that
laws used in
accusing and
convicting persons
of crimes must be
fair.