MENS REA ANDACTUSREUS
To obtain a criminal conviction, the prosecution must
establish the presence of two elements at the time of the
crime—namely,actus reus(“guilty act”) and mens rea
(“guilty mind”). A failure to show the presence of these
elements will lead to an unconditional acquittal of the
charged crime. Because both must be proven with evi-
dence beyond a reasonable doubt by the prosecution at
trial, the argument that there was no actus reus or mens
rea is not a defense per se. They are unlike various affir-
mative defenses, such as the insanity defense or self-
defense, which are viewed as excuses or justifications
for otherwise disfavored conduct.Actus Reus
Actus reus is the conduct requirement for a crime. The
actus reus requirement excludes from criminal liability
mere thoughts, a person’s condition or status (e.g.,
being an alcoholic as opposed to criminal behavior
committed while intoxicated), and involuntary acts.
Voluntary acts that satisfy this requirement include
positive conduct, omissions of required or reasonably
expected conduct, and possessions of criminally pro-
scribed objects. The definition of a voluntary act is
construed broadly to include any exercise of will; for
example, an individual acting under threats or pressure
is still considered to be acting voluntarily (although
this may constitute an affirmative defense of duress).
Acts that might be considered involuntary can be
divided into two categories: involuntary conduct and
impaired consciousness. The first category includes
physically coerced movements (e.g., someone pushes
an individual into a third individual, causing harm to
the third individual), reflex movements (e.g., the reac-
tion of a person suddenly stung by a swarm of bees),
muscular contractions caused by disease, and uncon-
scious acts. Medical conditions that may cause invol-
untary conduct include strokes, epilepsy, and narcolepsy.
These behaviors are all characterized by a break in the
mind–body connection that leaves the person’s
actions undirected by a conscious mental process.
Behaviors that fall within this category are more
widely accepted as lacking the actus reus component
than those in the second category.
The second category, impaired consciousness,
includes behaviors where there has been a sufficient
diminishment of the link between mind and body sothat the person is not consciously aware of the actions
being taken but can engage in goal-directed conduct
based on prior learned responses. Behavior during
such periods may be referred to as “automatic” and the
individual may be described as an “automaton.”
Temporary brain damage from a concussion and sleep
disorders such as night terrors are two common exam-
ples of impaired consciousness. Speculation has
centered on whether symptoms resulting from hypo-
glycemia should be included within this category.
Evidence of a mental disorder is almost never per-
mitted in conjunction with an assertion that the defen-
dant lacked actus reus. Instead, this evidence can be
used to support an insanity defense in those states that
allow volitional arguments (e.g., the defendant’s
behavior was the result of an irresistible impulse that
resulted from a mental disorder). Under the insanity
defense, if the individual’s inability to conform his or
her behavior with the law is the result of a mental dis-
order, the defendant can be acquitted and subsequently
committed for treatment, a result that cannot be
imposed on those acquitted due to a lack of actus reus.Mens Rea
Mens rea, or guilty mind, is the requirement that a
defendant possess a particular state of mind at the time
the crime is committed. The mens rea requirement for
a crime is usually represented in the relevant criminal
statute by one of the following terms:intent, purpose,
knowledge, recklessness,or negligence.Most criminal
statutes impose only a general or objective mens rea
requirement, where the inquiry focuses on whether a
reasonable person would have known that the act would
cause harm. To be convicted of a so-called general-
intent crime, the defendant must have known that he or
she was acting but not that any particular criminal
consequences would result from his or her act; this is
usually captured by the rubrics of “recklessness” or
“negligence.” To meet this requirement, the prosecution
does not have to explore the mental state of the defen-
dant. Other crimes require a showing of specific or sub-
jective mens rea, in which the prosecution must
establish that the defendant did actually know or intend
that a particular harm would result from his or her act.
Because this can be difficult to prove, specific or sub-
jective mens rea is usually reserved for more serious
crimes with more severe punishments.
Evidence of a mental disorder is rarely allowed in
cases involving general or objective mens rea, becauseMens Rea and Actus Reus——— 487M-Cutler (Encyc)-45463.qxd 11/18/2007 12:43 PM Page 487