Crim law 5-6

Factual defense

A defense arguing that the defendant did not commit the crime, such as an alibi or mistaken identity.

Justification

A defense admitting the act occurred but arguing that it was legally justified under the circumstances.

Excuse

Conduct that is illegal but forgiven, or punished less severely, because of the circumstances facing the defendant.

Perfect defense

A defense that completely eliminates criminal liability, usually resulting in an acquittal.

Imperfect defense

A defense that reduces culpability or punishment without completely eliminating liability.

Presumption of innocence

The defendant is presumed innocent until the prosecution proves guilt beyond a reasonable doubt.

Right against self-incrimination

The defendant cannot be forced to testify against themselves and does not have to testify to prove innocence.

Burden of production

The requirement to present enough evidence to raise a defense.

Burden of persuasion

The responsibility to convince the decision-maker that a defense has been established; who carries it depends on the defense.

Alibi

A factual defense claiming the defendant was somewhere else when the crime occurred.

Affirmative defense

A special defense raised by the defendant that can reduce or eliminate liability even if the defendant committed the act.

Burden of proof for self-defense

Once self-defense is raised, the prosecution must prove beyond a reasonable doubt that the defendant's force was unlawful.

Self-defense

A justification allowing reasonable force to protect yourself from imminent unlawful force.

Model Penal Code § 3.04

Force is justified when the actor believes it is immediately necessary to protect against unlawful force on the present occasion, subject to legal limits.

Five elements of self-defense

Unprovoked attack, imminent threat, threat of bodily harm, no safe retreat when required, and reasonable/proportional force.

Initial aggressor rule

A person who starts a fight generally cannot claim self-defense against the other person's reasonable response.

Escalation exception

An initial aggressor may claim self-defense if the other person escalates the conflict with excessive force.

Withdrawal exception

An initial aggressor may regain the right to self-defense by clearly withdrawing and communicating that withdrawal, if required, but the other person continues the attack.

Massachusetts withdrawal rule

The initial aggressor's withdrawal must be in good faith and communicated.

Imminent threat

The danger must be happening now or about to happen, not merely a past threat or possible future danger.

Proportional force

The force used must be appropriate to the seriousness of the threat. Deadly force generally requires a threat of death or serious bodily harm.

Deadly force

Force that a reasonable person believes is likely to cause death or serious bodily injury.

Retreat to the wall doctrine

A rule requiring a person to take a safe opportunity to retreat before using deadly force where the duty to retreat applies.

Duty to retreat in Massachusetts

Massachusetts is not a "stand your ground" state. It enforces a strict duty to retreat outside the home before a person may use lethal or deadly force in self-defense

Castle doctrine

A rule that a person generally has no duty to retreat from an attack inside their dwelling.

Massachusetts castle doctrine limitation

Massachusetts interprets “dwelling” narrowly; common hallways and outdoor areas generally do not count.

Stand-your-ground doctrine

A law removing the duty to retreat in places where a person has a legal right to be, provided the requirements for defensive force are met.

Stand-your-ground limitation

The doctrine removes only the duty to retreat; force must still be reasonable and proportional.

Defense of others

A justification allowing a person to use appropriate force to protect someone else from an unlawful attack.

Traditional alter ego rule

A traditional rule under which a defender's right to intervene depends on whether the person being defended would have been justified in using force.

Reasonable appearance rule

A rule allowing defense of others when the defender reasonably believes the other person is being unlawfully attacked and needs protection.

Defense of property

A justification allowing reasonable force to prevent trespass or protect or recover property.

Limits on force to protect property

Deadly force cannot be used solely to protect property. A person generally must request that a trespasser leave or property be returned unless an exception applies.

Authority-based defenses

Defenses involving conduct or force authorized by law, such as certain uses of force by police.

Modern rule on resisting arrest

Most states prohibit resistance; the Model Penal Code bars using force to resist an arrest known to be made by a police officer, even if the arrest is unlawful.

Massachusetts resisting-arrest rule

A person may not resist even an unlawful arrest. Resisting arrest can be charged separately from the original offense, even if the original charge is dismissed.

Necessity

A defense arguing that breaking the law was necessary to avoid a greater harm.

Choice of evils

The reasoning behind necessity: the harm avoided must outweigh the harm caused by the illegal act.

Limits on necessity

The defense may fail if the danger is not immediate, the illegal act does not directly address the harm, or the defense is unavailable under the applicable law.

Duress

A defense based on being coerced into committing a crime by a threat of unlawful force that a person of reasonable firmness would be unable to resist.

Civil disobedience

Breaking a law to protest injustice; a moral or political motive does not automatically establish the legal defense of necessity.

Mutual combat

A rule recognized in many states under which people who agree to fight generally are not liable for minor injuries resulting from the fight.

Consent as a defense

Consent can negate criminal liability when it is voluntary, knowing, and legally valid.

Invalid consent

Consent may be invalid if the person is legally incompetent, too young, unable to make a reasonable judgment, or pressured by force, duress, or deception.

Limits of consent/mutal cobbat

A person generally cannot consent to enslavement or serious bodily harm.

Necessity and creating the danger

A defendant generally cannot claim necessity if they negligently or recklessly created the dangerous situation.

Civil disobedience

Intentional, nonviolent lawbreaking to achieve a social or political goal. A moral or political purpose does not automatically make the conduct legally justified.

Direct vs. indirect civil disobedience

Direct disobedience violates the specific law being protested. Indirect disobedience breaks a different law to protest another issue.

Objective reasonableness in self-defense

The defendant's situation and perceptions matter, but the use of force must still be objectively reasonable. A defendant's personal belief alone does not automatically justify the force used.

Deadly force to protect property

Deadly force cannot be used solely to protect property; it is only potentially justified against a threat of death or serious bodily harm.

Insanity defense

A defense that argues mental disease or defect prevented the defendant from meeting the legal standard for criminal responsibility at the time of the crime.

M’Naghten test

The right-wrong test: because of a disease of the mind, the defendant did not understand the nature and quality of the act or did not know the act was wrong.

Irresistible impulse test

A defendant may qualify as legally insane if mental disease caused an inability to control their conduct, even if they understood the act was wrong.

Model Penal Code (MPC) insanity test

Also called the substantial capacity test. Due to mental disease or defect, the defendant lacked substantial capacity to appreciate the criminality or wrongfulness of the conduct, or to conform conduct to the law.

Durham test

A defendant is legally insane if the criminal act was the product of a mental disease or defect.

Guilty but mentally ill (GBMI)

The defendant was mentally ill at the time of the crime but did not meet the legal insanity test. The defendant is convicted and punished, with mental health treatment provided during incarceration.

Not guilty by reason of insanity (NGRI)

A verdict finding the defendant legally insane under the applicable test at the time of the crime. The person is acquitted of the criminal charge but may be committed for treatment.

Competency to stand trial

A defendant must be able to understand the proceedings and assist their lawyer. If incompetent, the trial is postponed until competency is restored.

Diminished capacity

A defense or argument that a significantly reduced mental capacity affected whether the defendant had the mental state required for the offense. It may reduce the charge or punishment but does not automatically lead to acquittal.

Intoxication defense

Argues that impairment from alcohol or drugs prevented the defendant from forming the required mental state. Whether it is allowed depends on the jurisdiction and the type of intent.

Voluntary intoxication

Impairment from a substance the defendant chose to consume. It may negate specific intent in some jurisdictions but rarely excuses the conduct entirely.

Involuntary intoxication

Impairment caused without the defendant’s informed choice, such as being drugged or tricked. It is more widely recognized as a possible complete defense.

Infancy defense

A defense based on the defendant’s young age and developmental immaturity, which may mean they cannot be held criminally responsible under the applicable rules.

Common-law infancy rule

Traditionally, children under 7 were conclusively presumed incapable of crime; ages 7–14 were presumed incapable, but the prosecution could rebut that presumption by showing understanding of wrongfulness.

Mistake of law

A misunderstanding of what the law permits or requires. Generally, not knowing that conduct is illegal is not a defense.

When can mistake of law be a valid excuse?

Under the MPC approach, when the law was not reasonably available to the public or when the defendant reasonably relied on an official legal statement later found to be wrong.

Mistake of fact

A misunderstanding of the facts that may negate the required mens rea. It is more likely to succeed when the mistaken belief means the defendant lacked the mental state required for the crime.

Entrapment

An affirmative defense claiming government agents induced the defendant to commit a crime the defendant otherwise would not have committed.

Subjective entrapment test

Focuses on the defendant’s predisposition: was the defendant already ready and willing to commit the crime before government contact? Used by the federal government and most states.

Predisposition

The defendant was already willing and ready to commit the crime before the government approached; this generally defeats the subjective entrapment defense.

Objective entrapment test

Focuses on the government’s conduct and whether its tactics would induce an ordinary law-abiding person to commit the crime. The defendant’s criminal history is generally irrelevant.

Statute of limitations

A legal deadline for bringing criminal charges. If the deadline expires, prosecution is generally barred, subject to exceptions.

Tolling

A pause in the statute-of-limitations clock, which extends the time available to bring charges.

Why do statutes of limitations exist?

They promote fairness because evidence can disappear, memories fade, and witnesses may become unavailable over time.

Crimes commonly without a statute of limitations

Murder, treason, and capital offense, some child abuse and sexual assault offenses may also have extended or eliminated deadlines depending on the law.

Kahler v. Kansas (2020)

States do not have to use one specific insanity test

Roper v. Simmons (2005)

No death penalty for crimes committed under 18

Miller v. Alabama (2012)

No mandatory life without parole for juvenile homicide offenders

Jacobson v. United States (1992)

Government must show predisposition existed before its campaign for the subjective entrapment test

Insanity Defense Reform Act of 1984

A federal law passed after the Hinckley verdict that tightened the federal insanity defense and placed the burden of proving insanity on the defendant

Insanity defense burden of proof: most states

In most states, the defendant must prove insanity, generally by a preponderance of the evidence.

Insanity defense burden of proof: federal courts

Federal law requires the defendant to prove insanity by clear and convincing evidence.

Insanity defense burden of proof: Massachusetts

Once lack of criminal responsibility is raised, the prosecution must prove criminal responsibility beyond a reasonable doubt.

Voluntary intoxication in Massachusetts

Voluntary intoxication is not a legal defense to general intent crimes in Massachusetts, but it can be used to challenge specific intent crimes if the impairment prevented the defendant from forming the required state of mind

Modern minimum age for juvenile court

About half of the states have no minimum age for juvenile court jurisdiction; the other half set one, usually between ages 7 and 13.

Massachusetts minimum age for juvenile court

12

Which entrapment test is more common?

The subjective test is used by the federal government and most states. The objective test is used by a minority of states and is endorsed by the MPC.

Police deception vs. entrapment

Police may generally lie or go undercover and offer an opportunity to commit a crime. Pressure, repeated contact, and emotional appeals may support an entrapment argument.

Statutes of limitations for sexual assault

Many states have extended or eliminated deadlines for sexual assault, particularly cases involving child victims and delayed disclosure.

Dan White case (1979)

White’s manslaughter conviction became associated with the controversial “Twinkie defense” and helped illustrate the use of diminished capacity to argue reduced criminal responsibility.

Lorena Bobbitt case The case illustrated the irresistible impulse test of insanity. Bobbitt was found not guilty by reason of insanity after injuring her husband, showing how a mental condition may be used as an insanity defense.