Necessity

Definition / Rule

Necessity (also called “choice of evils”) is a justification defense available when a defendant commits what would otherwise be a crime in order to prevent a greater harm. The defendant’s otherwise unlawful conduct is justified because it was the lesser of two evils. Unlike duress (which involves human threats), necessity traditionally arises from natural forces or circumstances — though the MPC does not draw this distinction.

Elements

Common Law Elements

1. Imminence — the harm the defendant sought to avoid was imminent
2. Greater harm — the harm avoided was greater than the harm caused by the criminal act
3. No reasonable alternative — no lawful alternative was available to avoid the greater harm
4. Causal effectiveness — the defendant’s act actually prevented or could prevent the harm
5. No fault — defendant did not negligently or recklessly create the situation requiring the choice
6. No legislative preclusion — the legislature has not addressed the specific situation in a way that forecloses the defense

MPC § 3.02 Elements

1. Defendant believed the conduct was necessary to avoid an evil (subjective)
2. The harm sought to be avoided is greater than the harm caused by the conduct (objective comparison, evaluated by the court)
3. No legislative purpose to exclude the defense in the situation
4. Defendant was not at fault in creating the emergency

Key difference from common law: MPC focuses on defendant’s belief (subjective), then requires the evil avoided to actually be greater (objective). MPC also does not restrict necessity to natural emergencies — it can apply to human threats (overlapping with duress).

Key Cases

• United States v. Bailey (1980) — Inmates escaped from federal prison citing brutal conditions; Supreme Court held necessity defense requires that defendant not have access to legal alternatives, including surrendering to authorities.
• The Queen v. Dudley and Stephens (1884) — Sailors killed and ate a cabin boy to survive at sea; English court rejected necessity as a defense to murder. Established that necessity is no defense to intentional killing of an innocent person (common law).
• Nelson v. State — Typical fact pattern: defendant drives without license because of medical emergency; necessity may apply.
• People v. Unger (Ill. 1977) — Prison escapee facing threats of sexual assault may raise necessity; imminence and alternatives are jury questions.

Limitations

• No defense to murder (most common law courts): Necessity does not justify intentional killing of an innocent person (Dudley & Stephens). MPC § 3.02 does not expressly exclude murder, leaving it to the harm comparison.
• Economic necessity: Courts routinely reject necessity claims based on poverty or economic hardship; the defense requires a specific, imminent emergency.
• Defendant must be blameless: If the defendant created the necessity through their own fault, the defense is unavailable or limited.

Policy

Consequentialist: The law should excuse actors who make rational choices minimizing overall harm. Punishing them would serve no deterrent purpose.

Autonomy: Actors in genuine emergencies should not be forced to choose between two harms and then punished for choosing the lesser one.

Critique: The defense can be abused to justify politically motivated civil disobedience. Courts often exclude the defense when defendants attempt to use it for anti-war or environmental protests, finding that legal alternatives existed.