Drug and alcohol intoxication, since the mid 1800's, is not itself a defense to a crime. Nonetheless, in many jurisdictions in the United States, drug and alcohol intoxication can be used to raise reasonable doubt about a specific intent that is an integral element of some crimes. All crimes, except strict liability crimes, necessitate both an act (actus reus) and criminal intent (mens rea). If there is no mens rea such as in an accident, an individual cannot be found guilty of a crime requiring criminal intent. This area of the law is complex, differs from state to state, and is much more complicated than the insanity defense. However this knowledge is important whenever forensic psychiatric evaluations are performed in jurisdictions that permit these defenses. It is important for more forensic psychiatrists to become familiar with these issues.
General criminal intent refers to the intent to perform the act. General intent can be negated only by an insanity defense. It is a complete defense, negating the entire mens rea (both general and specific intent). A defendant is found not guilty by reason of insanity. Drug and alcohol intoxication alone cannot be the basis for an insanity defense. In addition to general intent, many crimes require an additional specific intent. A specific intent is intent to do some further act or to achieve some additional consequence, in addition to the general intent to do the act. The concept of specific intent was developed as a means of taking drug and alcohol intoxication into account as a partial excuse. Drug and alcohol intoxication can be used to negate only the specific intent in specific intent crimes.
Mens rea defenses are partial defenses that can negate a specific intent and thereby result in a defendant being found guilty of a lesser-included crime. In those jurisdictions that permit such defenses, drug and alcohol intoxication can be used as evidence to raise reasonable doubt about a required specific intent. In some states, such evidence is used affirmatively to negate a required specific intent, and the defense is called "extreme emotional disturbance." Since the mid 1900's, originally in California and later in many other states, mental illness also was included as a way to negate specific intent. The defense became known as diminished capacity and referred to a defendant's capacity to have the specific intent required for a crime. If a diminished capacity defense is successful, the defendant is found guilty of a lesser included crime, thereby resulting in a lesser sentence.
Since it is not always intuitively obvious which crimes are specific intent crimes, it is important to consult with the attorney. Assault is a general intent crime even though it requires a specific mental state. The distinction was made because this offense too often is associated with intoxication. However, assault with intent to murder is a specific intent crime. If the intent to murder is negated by intoxication or mental illness, then a defendant is found guilty of only assault. Arson is a general intent crime, so it also cannot be negated by intoxication. Murder is a specific intent crime despite there being no further act required. Defendants lacking the specific intent required for murder are found guilty of manslaughter. The distinction between murder and manslaughter developed to prevent individuals who killed another in a drunken brawl from receiving an automatic death penalty.
Intoxication itself is no excuse for committing a crime. Since ancient times debate has existed as to whether intoxication should be partially excusing or whether it should increase the gravity of the crime. Saint Thomas Aquinas believed that intoxication should be partially excusing. In contrast, Aristotle thought the penalty should be doubled, since in addition to the crime, the intoxicated individual was setting a bad example for others.
Although voluntary intoxication cannot be used as a basis for an insanity defense, in some jurisdictions there is a concept of "settled insanity" resulting from a period of drug usage. Settled insanity does qualify for an insanity defense. In California "settled insanity" can result from drug or alcohol use over a period of several months or even hours as long as it is not just a temporary condition produced by recent, rather than long standing, use of drugs or alcohol. This concept in California dates back to the late 1800s.
Diminished capacity should not be confused with diminished responsibility whereby a sentence is reduced after a defendant has been found guilty of a crime. In federal jurisdictions, mental illness, but not drug and alcohol intoxication, can be a basis for a downward departure in sentencing. Confusingly, such diminished responsibility in federal law is called "diminished capacity." Also as result of a voter initiative and legislation in California, since the early 1980s, diminished capacity as such was abolished and replaced by "diminished actuality," referring not to the capacity to have a specific intent but to whether a defendant actually had a required intent. Most importantly, the expanded definitions of premeditation and malice required for murder were eliminated with a return to common law definitions.
The expanded definitions involved gradations of guilt that led to conviction for different crimes according to degree of blameworthiness, using aspects usually reserved for ALI insanity defenses. Forensic psychiatrist Bernard Diamond was influential in the development of the expanded definitions of malice and premeditation as well as the inclusion of mental illness in diminished capacity as a basis in addition to drug and alcohol intoxication for negating specific intent. The mental illness could be of a lesser nature than that required for an insanity defense. Stephen Morse in California was instrumental in the dismantling of the expanded definitions of premeditation and malice and a reduction in the psychiatrist's role in such cases. The new defense of diminished actuality often still is loosely called diminished capacity.
Mens rea defenses frequently are used in murder trials. According to English common law, the presence of malice distinguishes murder from manslaughter. Murder is a specific intent crime, so drug use or intoxication can be used to raise reasonable doubt about malice, premeditation and deliberation. In those states with degrees of murder, premeditation and deliberation usually distinguish first from second degree murder with malice distinguishing second degree murder from manslaughter. The states of mind of premeditation and deliberation can be negated by voluntary intoxication. In some states, the extreme emotional disturbance defense (an affirmative defense) can reduce murder to manslaughter by negating the specific intents required for murder.
Early in English common law malice meant "malice," but because of the difficulty in proving malice, express malice was re-defined to require only intent to kill. Also, the concept of implied malice, an even more indirect concept, developed. In California, implied malice can be proven by an objectively dangerous act and a subjective conscious disregard for human life despite awareness of the danger. The subjective aspect of implied malice is defined as a specific intent in California. This intent can be negated also by voluntary intoxication or mental illness. "Heat of passion," or an honest unreasonable belief about being in serious acute danger (imperfect self-defense), additionally can negate malice.
In many states, in drunk driving cases, the state of mind of an individual when taking the first drink is the determining factor and not the state of mind when a drunk driver killed an individual. For example, if a defendant had a prior drunk-driving conviction, he/she should have been aware of the potential danger to others. If the individual knew he/she would be driving yet still took the first drink, disregarding the clear potential danger to others, implied malice can be found, with a resulting conviction for second degree murder. It is evident that the law in this area is complex. Nonetheless, it is essential to become aware of the relevant law in any jurisdiction in which criminal forensic psychiatric assessments are made.
Laws differ from state to state. Some jurisdictions permit mens rea defenses but others do not. Crimes are defined differently in the various states. Since intoxication is such a common factor in most violent crime, efforts should be made to assess whether a defendant's intoxication negated a required specific intent in a particular case. Since the middle of this century, mental illness - even if of a lesser degree than that required for insanity defenses - also can be used for a mens rea defense. As can be seen, knowledge of the complex potential mens rea defenses is essential when evaluating a criminal defendant in jurisdictions that permit such defenses.