Criminal Law: Elements, Homicide, and Defenses
The Building Blocks
A crime requires actus reus (a voluntary act or qualifying omission), mens rea, concurrence, and causation. Classify mens rea: specific intent (purpose), general intent (knowledge/recklessness), malice, and strict liability. Specific-intent crimes include burglary, larceny, embezzlement, false pretenses, assault, attempt, solicitation, and conspiracy; voluntary intoxication and mistake defenses work only against specific intent.
Homicide
Murder is unlawful killing with malice aforethought, shown by intent to kill, intent to inflict serious bodily harm, reckless indifference (depraved heart), or felony murder. Felony murder requires an inherently dangerous or enumerated felony and a killing during its commission; the underlying felony must be independent of the killing. Manslaughter is voluntary (heat of passion, adequate provocation) or involuntary (misdemeanor manslaughter, criminal negligence).
Inchoate Crimes and Accomplice Liability
Attempt requires specific intent plus a substantial step. Conspiracy requires an agreement plus intent to achieve the objective; at common law no overt act is required, and the modern majority requires one. Withdrawal defeats future liability only if communicated and timely. An accomplice is liable for crimes he aids or encourages and for foreseeable crimes in the chain.
Defenses
Self-defense (reasonable belief, proportionality, retreat rules), defense of others, duress (not a defense to homicide), necessity, insanity (M'Naghten, irresistible impulse, ALI), and entrapment (government inducement plus lack of predisposition).
Traps
Legal impossibility is a defense; factual impossibility is not. Transferred intent applies to completed crimes. A felony-murder defendant need not have intended to kill. Rule of thumb: name the mens rea first, then match the defense.