Chapter 4
Criminal Law:
Substance and
Procedure

Four Broad Categories of the
Law

Substantive criminal law

Procedural criminal law
 Rules of evidence
 The law of arrest

The law of search and seizure
 Questions of appeal
 Jury selection
 Right to counsel

Civil law

Public law

Careers in Criminal Justice:
The Attorney

Duties and characteristics of the job

Job outlook
 Salary
 Opportunities
 Qualifications

Education and training

The History of Criminal Law

The common law

Mala in se
 Legislation

Mala prohibitum

Sources of Criminal Law
 Each jurisdiction defines “crime”

Law is constantly evolving
 Constitutional limits

All criminal law in the U.S. must conform to the U.S.
Constitution
 Laws that are too vague or broad
 A person’s status can’t be a crime
 Punishment can’t be cruel or capricious
 Constitution forbids bills of attainder
 Constitution forbids ex post facto laws

Classifying Crimes

The legal definition of a crime

Actus Reus

The criminal act

Failure or omission to act can be considered a crime
 Mens Rea

To be a crime, the actor must have criminal intent

Four levels of intent

Purposeful
 Knowing

Reckless
 Negligent

Strict liability crimes
— mens rea is not essential

Ignorance and Mistake

Criminal Defenses
 Excuse defenses

Duress

Insanity

Intoxication

Age

Entrapment
 Justification defenses

Consent

Self-defense

Necessity

The Law of Criminal
Procedure

Exclusionary rule

Fourth Amendment

Fifth Amendment

Sixth Amendment

Eighth Amendment

Fourteenth Amendment

Due process of law

Substantive due process

Procedural due process