Diminished Capacity Standards
Tanisha Hill-Jarrett
Forensic Neuropsychology
July 21, 2014
Elements of a Legal Crime
 A conclusion of criminal responsibility (guilt) for a criminal
offense requires proof, beyond reasonable doubt of two elements:
(1) Actus reus - the physical conduct associated with the crime
(2) Mens rea - “guilty mind” the mental state, or level of intent,
associated with the crime
 Dates back to 17th century: “actus non facit reum nisi mens sit rea”
 Translation: “An act does not make a person guilty of a crime unless
that person’s mind be also guilty”
 Prosecution’s responsibility to prove both elements
Diminished Capacity
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Diminished capacity: doctrine recognizes that although, at the time the
offense was committed, accused was not suffering from a mental disease
or defect sufficient to exonerate him or her from all criminal
responsibility, the accused's mental capacity may have been diminished so
that he or she did not possess the specific mental state or intent
essential to the particular offense charged.
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Diminished capacity is a mens rea (“guilty mind”) defense
Culpability is the issue at hand
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Distinction between insanity and diminished capacity defense
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The accused often considered less culpable because of lesser intent
Insanity seeks to exculpate due to accused inability to appreciate nature and
quality of crime
Also not to be confused with “diminished responsibility”
 Mental “disorder” that does not produce insanity or inability to form mens rea
Gradation of Diminished Capacity
 Definition ranges from conservative to radical based on evidence that is
considered admissible:
(1)
(2)
(3)
The presence of a mental disease or defect is admissible insofar as it impairs
an individual’s capacity to form the requisite specific intent to commit the
crime
Taking into account a vast number of personal characteristics of the
individual – anything that bears on the capacity to control one’s actions
Considering the person’s entire life history as well as potential predisposing
factors
Levels of Mens Rea
 Common Law terms
 General intent crime: require proof that perpetrator was/should have
been conscious of physical actions and their consequences (e.g.,
manslaughter, battery, rape)
 Specific intent crime: prosecutor must prove that the defendant
knowingly or purposefully committed act (e.g., “premeditated” murder,
“aggravated” assault, assault “with intent to rape)
 Attempts to simplify the mens rea by specifying four different mental
state “levels”
(1) Purpose – awareness and intentionality
(2) Knowledge – awareness of criminal nature, but unintended
(3) Recklessness – disregard of risk
(4) Negligence – unaware of risk
Operational Definition of Intentionality
 Malle & Nelson, 2003
 What are the conditions for an action to be intentional?
 Problems with inference of a “mental state”
 Conceptual
 Inferential
 Philosophical models describe an action as intentional if it caused by the
agent’s intention, which is itself based on the agent’s beliefs and desires
 Authors sought to develop an operational definition that is
representative of layperson’s beliefs
Operational Definition of Intentionality
Mental state
Action
(Intention independent of intentionality )
Awareness: The Issue of Automatism
 Semantic Ambiguity
 Legal: unconscious behavior (negating possibility of mens rea)
 Clinical: initially used in epilepsy literature to refer to set of
repetitive, involuntary, and unconscious behavior during ictal or
post ictal state (actus reus + mens rea)
 Can potentially encompass variety of situations: sleepwalking,
during seizure, while unaware secondary to head injury,
dissociative episodes
 Courts generally limit this defense when defendant should have taken
precautionary/preventative action
 Burden is on defendant to establish the defense
 http://youtu.be/1O-JXXSTNkU (Dan White + “Twinkie Defense”)
 Presumed unconsciousness – state of mind unknown
 Methodological obstacles of testing awareness
Automatism Defense
The Science of Conscious vs.
Unconscious Action
 Is there a scientific ability to distinguish conscious from
unconscious acts?
 At the crux of debate is human self control – are we slaves to
our emotions vs. free will
 To what extent are aggressive acts premeditated (suggesting
that they are intentional) and to what extent are they
committed impulsively or reactively?
 Barratt & Felthous, 2003 suggest
 Impulsive or reactive
 Premeditated or proactive
 Aggression secondary to medical (including psychiatric) disorders
Voluntary Intoxication
 Most common basis for diminished capacity is intoxication
 NIDA: One-half of all violent episodes in country mediated
in part by acute intoxication
 Montant v. Egelhoff (1996)
 Cannot introduce voluntary intoxication as evidence (always
admissible, however, in capital sentencing)
 Voluntary intoxication was traditionally rejected as a basis for a
criminal defense and, in fact, was often viewed as an aggravating
factor for purposes of sentencing
 An exception to this rule is “pathological intoxication”
Voluntary Intoxication Defense
4 approaches to use evidence of
voluntary intoxication to negate mens rea
 23% (n=12) Bar the use of such evidence
in all criminal cases to negate any element
of the offense
 38% (n=20) Have statutory language
which permits evidence of voluntary
intoxication, where relevant, to negate “an
element of the offense” (i.e., applying mens
rea component to general intent)
 40% (n=21) permit evidence of voluntary
intoxication to negate specific intent
 6% (n=3) admit evidence of voluntary
intoxication only in first degree murder
cases