Chapter 3
Criminal Law: Substance and Procedure
Definitions
 Substantive criminal law: refers to a type of law that defines crime
and punishment (penal codes)
 Procedural Criminal law: the rules designed to implement substantive
law (code of criminal procedures)
 Civil law: rule of law governing phases of human enterprise, including
commerce, family life, property transfer and regulation of
interpersonal conflict.
Historical Development of Criminal Law
 Babylonian Code of Hammurabi (2000 B.C.)
 Mosaic Code of the Israelites (1200 B.C.)
 Roman Twelve Tables (451 B.C.)
 Justinian’s Corpus Juris Civilis
 German Wergild
Historical Development of Criminal Law (cont.)
 Common Law: Incorporated customs, traditions, practices, and
common behavior into a standardized law.
 Stare Decisis: To stand by decided cases. Decisions in earlier
cases become the standard by which subsequent similar cases are
judged.
 Mala in se: crimes that are inherently evil (i.e. murder)
 Mala prohibita: prohibited wrongs (failure to pay taxes)
Sources of Criminal Law
 Common law, statutes, and case decisions
 Administrative rules and regulations
 Constitutional laws
Sources of Criminal Law (cont.)
 Ex Post Facto Laws
 Punish an act committed before the passage of the law
criminalizing it.
 Makes a crime more serious and authorizes greater punishment
than the law existing at the time of the act.
 Makes it easier to convict the offender than the law existing at the
time of the act.
Crimes and Classifications
 Felony: Serious crime punishable by imprisonment in a penitentiary
or death.
 Misdemeanor: A less serious crime punishable by fine or
imprisonment for less than a year.
 Infraction: Violations of a city or county ordinance normally punished
by a fine. Some states consider infractions to be civil rather than
criminal.
Legal Definition of a Crime
 Actus reus
 An illegal act.
 A failure to act when the law requires you to do so.
 Act must be voluntary.
 Negligent acts can result in criminal liability.
Legal Definition of a Crime (cont.)
 Mens rea –
 Guilty mind or intent. The mental element of a crime.
 Intent is implied if the results of an act are certain to occur.
 Crimes may require different levels of intent ranging from
purposely to negligently.
Legal Definition of a Crime (cont.)
 Strict liability offenses:
 Illegal acts that do not require a showing of intent.
 Examples:
 Speeding.
 Serving a minor alcohol because he/she looked older.
Criminal Defenses
 A person can commit an act that would ordinarily be a crime but they
are not held criminally liable because there is a recognized defense
or justification for their act under the law.
Criminal Defenses (cont.)
 Ignorance or Mistake
 As a general rule ignorance of the law is not a defense.
 Mistake of fact may be a defense if it shows a lack of intent.

Taking someone else’s coat because you believed it was
yours.
Criminal Defenses (cont.)
 Insanity
 Relies on a legal rather than medical definition.
 Defendants who are legally insane are found not guilty by reason
of insanity.
Criminal Defenses (cont.)
 Intoxication
 Voluntary intoxication is not normally a defense.
 Involuntary Intoxication may be a defense.
Criminal Defenses (cont.)
 Age
 A child is not criminally responsible for actions committed at an
age that precludes a full realization of gravity of certain types of
behavior.
 Under the common law a child under the age of seven was
presumed to be incapable of forming intent.
 Today state statutes establish this age.
Criminal Defenses (cont.)
 Consent
 A person may not be convicted of a crime if the victim consented
to the act.

A forcible rape does not occur if person consents to sexual
relations.

A statutory rape does occur, even if the parties consent
because the law assumes not all persons are capable of
giving consent.
Criminal Defenses (cont.)
 Self-defense
 Must have acted under reasonable belief that he/she was in
danger of death or great harm, and had no means of escape
 May only use such force as is reasonable necessary to prevent
personal harm
Criminal Defenses (cont.)
 Entrapment
 Police may provide someone with the opportunity to commit a
crime.
 May not induce someone to commit a crime they otherwise would
not do through the use of traps, decoys, and deception.
Criminal Defenses (cont.)
 Duress
 Person is forced to commit a crime in order to prevent death or
serious physical harm to themselves or someone else.
 Generally may not claim duress as a defense or justification to
the crime of murder.
Criminal Defenses (cont.)
 Necessity
 In order to prevent a greater harm a crime is committed. Must be
able to show that any reasonable person would have done so.

Breaking into a closed store to call an ambulance.
 Generally does not apply to social or moral agendas.

Shutting down nuclear power plants or abortion clinics.
Reforming Criminal Law
 The federal and state governments consistently make efforts to
reform the law to ensure it reflects the needs of society.
 Advances in technology or new social factors require creation of
additional laws.
 Changes in society may dictate decriminalization of certain acts.
 Defenses and justifications undergo similar changes.
Constitutional Criminal Procedure
 Substantive criminal law primarily defines crimes.
 Procedural criminal law consists of the rules and procedures that
govern the pretrial processing of criminal suspects and the conduct
of criminal trials.
 Main source of procedural law is the Bill of Rights (1st ten
amendments to the Constitution).
Constitutional Criminal Procedure (cont.)
 Fourth Amendment: Regulates searches and seizures.
 Fifth Amendment: Protects against self-incrimination, double
jeopardy, and guarantees right to grand jury.
 Sixth Amendment: Right to a speedy and public trial by an impartial
jury, right to counsel, notice of charges, and confrontation of
witnesses.
 Eight Amendment: Prohibits excessive bail, excessive fines, and
cruel and unusual punishment.
 Fourteenth Amendment: Makes Bill of Rights applicable to the states.
Due Process of Law
 Found in both the 5th and 14th Amendments.
 Refers to the essential elements of fairness under law.
 Substantive due process protects against laws that are unfair.
 Procedural due process ensures no one is deprived of life, liberty, or
property without proper and legal criminal process.
Due Process of Law (cont.)
 Notice of charges
 A formal hearing
 The right to counsel/representation
 Opportunity to respond to charges
 Opportunity to confront and cross-examine witnesses
 Free from self-incrimination
 Opportunity to present one’s own witnesses
 A decision made on the basis of substantial evidence and facts produced at
hearing
 Written statement of reasons for the decision
 An appellate review procedure