federal, state, and municipal jurisdictions establish sources of criminal law— most commonly through statute—which outline the elements necessary for a defendant to be found guilty of a crime. Criminal guilt is established only if the prosecution can demonstrate and prove all of the required elements of the crime charged. The prosecution must prove each required element of the crime to the standard of beyond a reasonable doubt in a criminal trial. A defendant is to be found not guilty of a crime if the prosecution fails to prove all of the required elements of the crime or if the defendant establishes an affirmative defense to the crime.
In general, for a defendant to be guilty of a crime, two elements must be established and proven by the prosecution: the actus reus (Latin: “prohibited act”) and the mens rea (guilty mind—the intent to commit the actus reus). The actus reus is further defined as either a voluntary physical act commit- ted by the defendant or the defendant’s failure to act when there was a legal duty to act. The law is usually concerned with preventing individuals from committing a harmful act to another. However, there are some obligations imposed by the law, such as a parent must provide food and shelter to a child, and failure to do so would constitute an actus reus. Both the actus reus and the mens rea must occur together in order to constitute a criminal act.
For example, person A is angry and intentionally strikes person B. A is charged with Battery. The actus reus is A striking B. The mens rea is A’s purposeful intent to strike B, motivated by A’s anger at B. In this example, A could be convicted of Battery. In a contrasting example, A strikes B as the result of an unintentional bump. A has struck B, therefore a forbidden act has occurred. But because the striking was accidental, no mens rea is present and no criminal liability exists (although civil liability may result). For nearly all crimes, the prosecution must prove the requisite mental state (mens rea). An exception is strict liability offenses, such as Statutory Rape or Driving Under the Influence, which require only an actus reus to result in a criminal conviction.
The concept of mens rea is important because the criminal law recognizes that a person who intends to harm another is more blameworthy than the person who accidentally harms another [1] . It is important to note that a defendant with a major mental illness may still be able to form the requisite level of mens rea for a given crime. Mentally ill defendants may intention- ally commit criminal acts that occur for reasons and motives independent of their mental illness. For example, a psychotic individual may still pur- posely assault another for reasons unrelated to his psychosis, such as anger, revenge, financial gain, etc.
Even if the prosecution establishes all of the criminal elements (actus reus and mens rea) beyond a reasonable doubt, the defendant my nevertheless avoid criminal responsibility by raising an affirmative defense. An affirma- tive defense is a legal defense in which the defendant affirms that he indeed
committed the actus reus, but, due to the special conditions alleged via the affirmative defense, seeks an acquittal. An affirmative defense justifies or excuses a criminal defendant of legal responsibility even though the ele- ments of the crime have been proved. A state may, at its discretion, place the burden of proof for establishing an affirmative defense on either the prosecution or defense. Some affirmative defenses are legal justifications for the criminal act, such as in self-defense. The law recognizes that harm to another may be justified when a person is defending against imminent phys- ical harm. Another category of affirmative defenses are legal excuses. The defense of NGRI falls into this category. For these, society has determined that the defendant is not blameworthy of the criminal act, usually based on a moral ground. Table 6-1 lists common affirmative defenses.
In this example, Frank committed a criminal act (actus reus), shooting and killing a person. At the time of his act, Frank’s mental state was such that he intended to cause death (mens rea). The challenge for an evaluator, and ultimately for the court, will be to evaluate whether Frank should be legally excused by the affirmative defense of insanity because he perceived
Table 6-1. EX AMPLES OF AFFIRM ATIVE DEFENSES • Automatism (unconsciousness) • Duress (compulsion) • Entrapment (inducement by law enforcement) • Necessity (justification due to emergency) • Not guilty by reason of insanity • Self-defense (danger of imminent bodily harm) • Statute of limitations (expiration of time to pursue prosecution) VIGNETTE 1
Frank has been diagnosed with Schizophrenia. He experiences inter- mittent auditory hallucinations and is routinely noncompliant with his psychotropic medications. Frank is very religious and frequently reads the Bible for hours. He develops a belief that his mother has been taken over by Satan. Frank finds his father’s firearm and shoots and kills his mother based on his delusional belief that he must kill Satan to save his mother. Frank’s brother arrives home hours later and finds his mother dead with Frank praying over her. Will Frank be convicted of murdering his mother?
himself as killing Satan and not a human. Forensic mental health profes- sionals are commonly called to evaluate such defenses because of their knowledge of and experience in evaluating mentally ill individuals and ability to evaluate a defendant’s mental state at the time of the offense. This specialized expertise will be explored further in later portions of this chapter.