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Flashcards in Defenses Deck (23)
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What are the two general types of defenses for specific intent crimes?

  1. Capacity (insanity, intoxication, etc)
  2. Justification (self-defense, etc)


What are the tests for insanity?

  1. M'Naghten;
  2. Irresistible Impulse;
  3. Durham/New Hampshire test; and
  4. Model Penal Code standard


Elements of M'Naghten test

  1. D suffered from a mental disease or defect in reasoning; and
  2. D was unable to understand the "nature and quality" of his act OR that what he was doing was wrong



Irresistible Impulse test

Looks at whether D is incapable of controlling his behavior.

⭐️ Many states use both M’Naghten & the Irresistible Impulse test.



Durham/New Hampshire test

D will be acquitted if his actions were the product of a mental disease or defect ("but for")


What is the MPC test for insanity?

As a result of mental disease or defect, D lacks substantial capacity to either:

  • Appreciate the criminality of his conduct; or
  • Conform his conduct to the requirements of the law

⭐️ Note: Success under either the M'Naghten test or Irresistible Impulse test will satisfy the MPC standard.


What are justification/excuse defenses?

Argues that D's conduct was justified under the particular facts of the case. Includes:

  • Self-defense;
  • Defense of others;
  • Defense of property;
  • Necessity;
  • Duress;
  • Crime prevention, arrest and to prevent escape; and
  • Entrapment



Elements of self-defense 

  1. D honestly and reasonably believed; 
  2. That he was subject to an imminent unlawful use or threat of force; and
  3. D used proportional force to defend himself



When can first aggressors claim self-defense?

  1. They have completely withdrawn, communicated that to V, and V reattacks/continues attacking; or
  2. They used nondeadly force and V responded with deadly force


Can V act negligently when using self-defense?

No, V may not act in a manner than a reasonable person would find inappropriate


castle doctrine

A person in his or her own home has no duty to retreat from the use of deadly force for protection


When can D invoke a defense of others claim?

If D:

  1. Reasonably believed V was in imminent danger of great bodily harm;
  2. Used force proportional to prevent the harm; and
  3. Reasonably believed V would have had a right of self-defense


When is the defense of property allowed?

Non-deadly force is justified if: 

  1. D has a reasonable belief that the property is in imminent danger; and
  2. D did not use more force than what was necessary to prevent the interference


Can you use deadly force to protect property? 

No, unless: 

  1. Intruder has broken into dwelling (i.e. your occupied home); 
  2. There is reasonable fear of an immiment felony being committed; and 
  3. Force is necessary to prevent such intrusion 

⚠️ Modern view: deadly force to protect one's home is only allowed if D has a fear of an immiment violent felony being committed (e.g. homeowner sees intruder with a gun)


Elements to the defense of necessity

  1. There is an immediate threat of greater harm to persons or property unless D commits the act;
  2. No reasonable alternative to breaking the law; and
  3. D is not responsible for causing the intial harm

⚠️ Note: Economic necessity is not valid justification



Elements for duress defense

  1. Imminent threat by third party;
  2. Of serious great bodily harm or death; 
  3. That reasonably causes D to become fearful;

⚠️ Note: Duress is not allowed as a defense for homicide


Is voluntary intoxication a defense?

No, unless used to show that D could not have formed or possessed the requisite intent for a crime (i.e. only for specific intent crimes)



Is involuntary intoxication a defense?

Yes, as either temporary insanity or negation of requisite intent (either general or specific)


What qualifies as involuntary intoxication?

Taking a substance:

  • Under duress; or
  • Without knowledge of its effects (lack of knowledge must be reasonable)


Is consent a valid defense? 

Yes, only if:

  • Consent is an element of the crime; or 
  • Consent is for non-serious bodily harm that occurs during a lawful athletic activity or competition


  • The consent was voluntarily given by a person with legal capacity to consent



Elements of entrapment defense 

  1. Government designed the crime and encouraged its commission; and
  2. D was not predisposed to commit the crime prior to engagement with law enforcement

⚠️ Very limited defense that rarely works


Is mistake of law a valid defense?

Generally not. Only successful in extremely rare circumstances if: 

  • D reasonably relied on a statute that is invalid; or
  • Crime requires knowledge of the law itself (ex. crime requires D to "willfully" violate it; often applies to complicated tax laws)


Is mistake of fact a valid defense?

Only if the mistake prevented D from having the requisite mens rea for the crime

⚠️ Note: Mistake can be either reasonable or unreasonable