Individuals are responsible for their actions and must be held accountable for them.
Certain individuals may lack capacity to appreciate the wrongfulness of their conduct.
Factors beyond individuals’ control may lead them to commit criminal acts. In such instances the law exempts individuals from responsibility.
There are situations in which acts that would otherwise be crimes may be justified (e.g., homicide in self-defense).
Types of Defenses Basis of Defense Examples Asserting lack of capacity Insanity, intoxication Excuse or justification Duress, necessity, mistake Use of force Self-defense, defense of others, defense of home Constitutional/statutory authority Double jeopardy, statute of limitations Improper governmental conduct Entrapment, selective prosecution
The common law regarded a child under age seven as incapable of forming criminal intent.
This presumption of incapacity was rebuttable regarding a child between seven and fourteen years old, with the prosecution having the burden to demonstrate that a child younger than fourteen was capable of comprehending the wrongdoing involved in an offense.
Children over age fourteen were treated as adults.
Involuntary intoxication relieves the criminality of an act committed under its influence if, as a result of intoxication, the defendant no longer knows right from wrong.
In most jurisdictions, voluntary intoxication may be considered in determining whether a defendant can formulate the specific intent the prosecution must establish in such crimes as larceny, burglary, and premeditated murder.
Most courts reject the defense of voluntary intoxication for general-intent crimes.
“ It must be clearly proved that, at the time of committing the act, the party accused as labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of the act he was doing; or, if he did know it, that he did not know what he was doing was wrong.”
By the mid-1800s, the M’Naghten Rule had become the test for insanity used in both federal and state courts in the United States.
In 1962, the American Law Institute (ALI), proposed a new standard sometimes referred to as the substantial capacity test.
It provides that “a person is not responsible for criminal conduct if at the time of such conduct, as a result of mental disease or defect, a person lacks substantial capacity either to appreciate the wrongfulness of his conduct or to conform his conduct to the requirements of the law.”
Few cases have caused as great a concern over the functioning of the criminal justice system in the United States as the verdict of “not guilty by reason of insanity” in the federal court trial of John Hinckley for the 1981 shooting of then President Ronald Reagan.
The Hinckley verdict motivated Congress and several state legislatures to review the status of insanity defenses.
Dissatisfied with the ALI test, which was applied in the Hinckley trial, Congress decided to eliminate the volitional prong in the federal test for insanity and to revert substantially to the M’Naghten Rule.
“ It is an affirmative defense to a prosecution under any federal statute that, at the time of the commission of the acts constituting the offense, the defendant, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts. Mental disease or defect does not otherwise constitute a defense.”
A pattern of psychological and behavioral symptoms of a woman living with a male in a battering relationship.
Some jurisdictions now permit a female in that situation who is charged with assaulting or killing a man to show that even though she did not face immediate harm, her plea of self-defense should be recognized because her actions were her response to constant battering.
Where there is evidence that a child has been abused continually over an extended period, there is a movement now to assert the battered child syndrome in defense of a child accused of assaulting or killing a parent.
At common law, one had the right to use reasonable force to prevent commission of a felony or to protect members of the household.
The trend in American jurisdictions is to allow a person “to stand in the shoes of the victim” and to use such reasonable force as is necessary to defend anyone, irrespective of relationship, from harm.
If a defendant appeals from a conviction and prevails, it is not double jeopardy for the prosecution to retry the defendant, unless the appellate court rules that there was insufficient evidence to sustain the defendant’s conviction.
Nor is it double jeopardy to retry a defendant if the trial court has declared a mistrial on the motion of the defense.
If the government moves for a mistrial, the defendant objects, and the court grants the mistrial, the prosecution must establish a manifest necessity for the mistrial for a retrial to be permitted.
Under international law, a person who has diplomatic status and serves as a part of a diplomatic mission, as well as members of the diplomat’s staff and household, is immune from arrest and prosecution.