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CRJU: Criminal Law Online

A course guide of open education resources for faculty teaching Criminal Law.

Overview and Objectives


In this module, we study the various defenses that may be raised by the accused. 

Learning Objectives

After completing this module, students should be able to:

  • Distinguish between defenses based on justifications (focusing on the act) and excuses (focusing on the actor)
  • Identify the elements required for justification defenses (Self-Defense, Defense of Others, Defense of Habitation, Necessity)
  • Identify the elements required for excuse defenses (Insanity, Infancy, Diminished Capacity, Intoxication, Duress)
  • Compare the four insanity tests used across various jurisdictions
  • Discuss contemporary defenses recently used as criminal defenses (Affluenza, Battered Woman Syndrome, PMS)




Experts Determine State of Mind (from Films on Demand)


The legal system deals with the state of mind of the defendant at the time of the crime. Experts must determine if the crime is impulsive and if the behavior is typical of the defendant.

Brain Scans Support Diminished Capacity Defense (from Films on Demand)


Brain scans became admissible as evidence in court in 1993, leading to a diminished capacity defense with reduced penalties in murder cases. Brain scans provide an effective tool in illustrating a vulnerability to violence in criminals. An ABC News Production.


Crime and Insanity (from Films on Demand)


Is a psychiatric evaluation precise enough to be allowed as testimony in a court of law? U.S. Court of Appeals judge Irving Kaufman, Hastings Center president Willard Gaylin, and others discuss the use of psychiatry in law.



An overview of various aspects of criminal defenses, including denial, affirmative, perfect, imperfect, common law, statutory, justification, excuse, self-defense, and defense of habitation.

Categories to Defenses to Crimes Justification, Excuse, Mitigation Part 1 of 3.. Justification, Excuse, Mitigation

Case Examples

Lionel Tate Case: Judge, lawyer in Lionel Tate case reflect on landmark trial, cite regrets

CNN's Gary Tuchman reports on a woman who is serving 20 years in prison after her "stand your ground" defense failed.

CNN's Randi Kaye reports on case of boy who used the "affluenza" defense in case of killing four while driving drunk.

Ahmaud Arbery, an African American man in Georgia, was shot and killed by two white men. Omar Villafranca reports.