Table Of Content1
INTRODUCTION TO FORENSIC
PSYCHOLOGICAL PRACTICE
Forensic psychology may be defined as the interface between psychology
and law. The word forensic is a Latin derivative of the word meaning forum,
a place where trials were held in ancient Rome. The purview of forensic
psychology continues to expand, demonstrating the breadth and differentiat-
ing scope of practice in this specialty field. Although initially practitioners
in forensic psychology were generally clinical psychologists, now many
forensic psychologists receive training and practical experience in this spe-
cialty as graduate students and in postgraduate fellowships in forensic set-
tings. Today, more than 2,000 psychologists are members of the American
Psychological Association's Division 41, the American Psychology-Law
Society.
Hugo Munsterberg (1908) is generally credited with developing the
field of forensic psychology. In a seminal book called On the Witness Stand,
he reported, largely on the basis of his own experiences, how the knowledge
base of psychology can be used to help the court in several defined areas
(e.g., witness memory, the value of hypnosis in crime detection, and witness
interrogation). The book contains no reference citations, and his claims
were largely exaggerated and were not based on empirical evidence, but
Munsterberg's book served as a beginning point for the empirical study of
law and psychology.
Forensic psychology has two broad areas of application: research and
practice. The research boundaries are porous and continue to expand. Some
forensic research crosses over into other areas of psychological research,
particularly social psychology. Research activities of forensic psychologists
include the study of eyewitness memory and the conditions under which it
deteriorates or maintains reliability, jury decision-making processes, whether
the presence of an attorney is truly a safeguard for the defendant's rights at
a lineup, legal definitions such as reasonableness in the "reasonable person"
standard, criminal behavior, the variability of jury awards in sentences by
race of defendant and by jury instructions, and privacy rights.
Most of forensic practice has occurred in one of three main functions:
(a) friend of the court (amicus curiae) activities, (b) consultation, and
(c) acting as an expert witness (Blau, 1998). Some areas of forensic practice
overlap with areas of clinical psychology, particularly those pertaining to
psychological evaluations necessitating psychological tests. Some of the
activities that constitute forensic psychological practice include (but are
not limited to)
• providing child custody evaluations,
• screening police applicants,
• screening applicants for public safety jobs, such as access to
nuclear power plants,
• evaluating sex offenders,
• evaluating various insanity pleas,
• evaluating defendants in capital cases,
• providing services (treatment, intervention, prevention) to
offenders and correctional staff, and
• providing courtroom testimony.
This book addresses only professional forensic practice and does not
deal with forensic psychological research, except to describe the research
that underpins this practice. This book also concentrates on the assessment
of adults and on adult offenders, although material on the assessment of
juvenile offenders is occasionally included as well.
PREPARATION FOR FORENSIC PSYCHOLOGICAL PRACTICE
Forensic psychological practice inevitably involves depositions and
courtroom testimony. To best serve their clients, forensic psychologists
normally require the following preparation:
1. A doctoral degree from a school of psychology accredited by
the American Psychological Association must be completed.
PERSONALITY-GUIDED FORENSIC PSYCHOLOGY
2. State licensure or registration is required by all.
3. Direct and relevant experience in the matters before the court
is mandatory. For example, if substance abuse is an issue in
the court proceeding, then the psychologist must be able to
demonstrate expertise in alcohol and drug abuse screening,
evaluations, and treatment. If posttraumatic stress disorder
(PTSD) is an issue, the psychologist must be able to demon-
strate competence and knowledge in the full range of the
disorder. Demonstrating that one has evaluated and treated
a sufficient number of PTSD cases so as to be able to render
a believable conclusion on demand might reflect this
competence.
4. Attendance at continuing education workshops, seminars,
symposia, and the like is evidence of continuing involvement
in an area of expertise and is further evidence of competence.
5. Attainment of advanced specializations and certifications of
competency, such as diplomate status (clinical or forensic) or
fellow status granted by external bodies is additional evidence
of expertise. For example, if the psychologist testifies as an
expert in psychological testing, then fellow status in APA
Division 5 (Evaluation, Measurement, and Statistics) or fellow
status in the Society for Personality Assessment would be a
recognized credential. Normally, fellow status in serious profes-
sional organizations requires that one have a national reputa-
tion in a body of knowledge, have significantly contributed
to the advancement of that knowledge and skill, or have
demonstrated competency in practice applications as attested
to by one's peers.
6. Membership in relevant professional organizations (Otto &
Heilbrun, 2002) is helpful as well as publication of relevant
material, preferably in peer-reviewed journals, that adds to
scientific discovery.
To function within the best practice parameters of the psychology
profession, forensic psychologists must be aware of and knowledgeable
about legal issues, legal standards, legal definitions and terms, and legal
procedures. They must also be aware of the unique ethical issues that
affect forensic practice. Various sources of information about applicable
statutes and procedures are available (Van Der Velde, 1999), and a code
of ethics for forensic practice has been developed (Committee on Ethical
Guidelines for Forensic Psychologists, 1991). Also, there are journals that
are specifically devoted to forensic issues; among the more frequently
cited are the following:
INTRODUCTION
• American Journal of Forensic Psychology,
• Behavioral Sciences and the Law,
• Criminal Justice and Behavior,
• Law and Human Behavior,
• Journal of Forensic Psychology Practice,
• Psychology, Public Policy, and the Law,
• Journal of Psychiatry and Law,
• Journal of Threat Assessment,
• American Journal of Forensic Psychiatry,
• Journal of the American Academy of Psychiatry and Law,
• Journal of Forensic Psychiatry and Psychology, and
• Rules of Evidence.
In Jenkins v. United States (1962), the court ruled that psychologists
may testify as expert witnesses on mental disorders as long as they have
appropriate training and expertise. Three psychologists had testified pertain-
ing to a defendant's mental disease. The trial judge instructed the jury to
disregard the testimony of the psychologists because they were not physicians.
On appeal, both the American Psychological Association and the American
Psychiatric Association filed amicus curiae briefs. The psychology association
argued that psychologists were professionally qualified to diagnose mental
illness, whereas the psychiatry association argued that although psychologists
may be good testers, they function only as assistants to psychiatrists and
are not qualified to diagnose or treat mental illness.
Judge David Bazelon ruled that it was not a medical degree that
conferred expertise on the question of mental disease, but rather a person's
training, skills, and knowledge. He ruled that psychologists did have these
necessary requirements and therefore could serve as expert witnesses in the
case, as long as they become familiar with rules of evidence that allow certain
kinds of testimony to be admissible (or inadmissible) in court proceedings.
Rules of evidence vary across jurisdictions. State courts rely on either
codified rules of evidence or extensive case law, and some use the federal
rules of evidence as a model. In federal courts, the admissibility of scientific
evidence may rely on one of three legal standards:
1. In the Federal Rules of Evidence (FRE, 1992), the evidence is
admissible if it is relevant and helpful.
2. In the Frye standard (United States v. Frye, 1923), the court
ruled that if a test, methodology, or procedure has general
acceptance in the field to which it belongs (e.g., scientific
community), then it can be admitted in court.
3. In 1993 the Supreme Court clarified that the FRE should be
used in federal courts and then outlined the standards that
the courts could use. In Daubert v. Merrell Dow Pharmaceuticals
PERSONALITY-GUIDED FORENSIC PSYCHOLOGY
(1993), the court ruled that the trier of fact (judge or jury)
must make a preliminary assessment as to whether the expert's
reasoning and methodology are scientifically valid and can be
properly applied to the facts at issue in the court. This new
standard now compels the forensic psychologist to pay far
more attention to issues of reliability and validity and to
other technical matters (e.g., operating characteristics and
diagnostic power) of the psychometric instruments on which
the testimony is based.
The U.S. Supreme Court has subsequently clarified and elaborated on
the interpretation of the Daubert standard in General Electric v. Joiner (1997)
and Kumho Tire Company Ltd. et al. v. Carmichael et al. (1999). In General
Electric, the court ruled that a judge's determination on Daubert admissibility
may not be overturned unless the judge has abused the discretionary author-
ity. In Kumho, the court ruled that the requirements of Daubert do not have
to be met in every case and that judges have wide discretion in determining
a method's reliability. No doubt there will be increasing refinement, interpre-
tation, and application of the FRE and Daubert in subsequent court reviews.
The FRE was modified as of December 1, 2000 but continues to rely
on Daubert. This revision requires that the testimony be based on scientific
facts or data and be the product of reliable principles and methods and that
the expert witness have applied the principles and methods reliably to the
facts of the case. These conditions continue to be modified by case law and
subject to interpretation.
Daubert relies on scientific philosopher Karl Popper's criteria for the
falsifiability of scientific theories. Popper's theorem states that a scientific
theory should be so operationally (and concretely) defined that it can be
tested and found false. The court also suggested additional criteria: Has the
theory or technique been subjected to peer review and published in scientific
journals? Is there general acceptance of the theory or technique in the
scientific community? Does the theory or technique have a known error
rate, and are there standards to control for this error rate? The court stated
that these criteria were not meant to be exhaustive, but it did not rule that
a test or theory had to meet all four elements of the criteria in order for
the testimony to be admissible in court.
Professional standards also apply to this stricture. Psychologists practice
according to specialty guidelines (American Psychological Association,
1981) and the American Psychological Association (2002a) Ethical Principles
of Psychologists and Code of Conduct (Ethics Code), which prescribe general
ethical psychological practices and address assessment practice. Heilbrun
(1992) published recommended criteria to use in judging the adequacy of
a psychological test for purposes of court testimony. Heilbrun's guidelines,
INTRODUCTION
which are increasingly being referenced in the professional literature and
may become the standard in the future, are as follows:
• Is the test commercially available, with a manual and at least
one independent review?
• Is the test's reliability (interrater and test-retest) at least .80?
• Is the test relevant to the legal issue or to a psychological
construct underlying the legal issue?
• Does the test have a standard method of administration, and
should it be administered as close as possible to this standard?
• Is the test applicable to the population and purpose for which
it is being used?
• Does the test have objective scoring criteria, and does it have
actuarial data that can combine scores, which is preferable?
• Does the test measure response styles?
It is advisable for the forensic psychologist to apply these criteria, as well
as the Daubert standard, to each method used on which there may be court
testimony. Forensic psychologists should also expect cross-examination on
each of these criteria and on the methods used, and they should prepare
rebuttal arguments to these challenges. Consultation with a competent
attorney should be quite helpful with this rebuttal process, especially in
depositions where an attorney's line of attack is revealed, thereby allowing
the psychologist to prepare rebuttal arguments during actual court testimony.
The FRE governs the admissibility of expert testimony in federal courts.
State courts have individual determinations for admissibility of evidence,
although most rely on some or all aspects of the FRE, Frye, and Daubert.
It is advisable for the psychologist to consult with an attorney to ascertain
what may or may not be introduced into evidence on the basis of state law.
TESTIMONY ON THE ULTIMATE ISSUE
Controversy exists concerning the issue of testifying as to the ultimate
(legal) issue in the case (e.g., Was the person legally insane? Was he or she
able to maintain mens rea?). Some jurisdictions permit such testimony by
experts, whereas others prohibit it, deferring such judgments to the triers
of fact. Some psychologists argue that they should reject pressure to testify
as to the ultimate issue, that their training generally does not provide
sufficient competence training and development to offer conclusions in
matters of law. However, there is some evidence that judges want expert
opinion on ultimate issues (Melton, Petrila, Poythress, & Slobogin, 1997).
PERSONALITY-GUIDED FORENSIC PSYCHOLOGY
Psychologists should consult with the hiring attorney about the limits of
their testimony.
CRIMINAL DEFENSES
Most criminal statutes include elements pertaining to conduct and
mental state in terms of mens rea, or level of intent to commit a specific
act, which includes knowledge and purpose. Some states also include the
specific circumstance or result of the criminal act in their statutes.
Defendants have a limited number of possible pleas that can be entered
in a criminal case, other than guilty. Psychologists working in the courts
should have a rudimentary knowledge of these pleas and a more thorough
knowledge regarding insanity pleas, if they conduct insanity evaluations.
The reader is urged to consult more exhaustive sources for a thorough
explanation of these defenses (e.g., Goldstein, Morse, & Shapiro, 2003).
The following are the most common defenses entered into the court:
1. Duress: With a duress plea the defendant argues that he or
she was threatened with death or serious bodily harm unless
he or she engaged in the criminal behavior.
2. Extreme mental or emotional disturbance: With this plea, duress
and extreme provocation result in the criminal act. Battered
wife syndrome, addressed in chapter 8, is a good example of
this type of plea.
3. Involuntary intoxication: Most statutes that allow involuntary
intoxication as a plea (and excuse for the criminal act) also
stipulate that it must have caused a mental abnormality that
meets the legal definition of insanity for the defendant to
avoid culpability.
4. Provocation or pressure: In this plea it is argued that the
criminal behavior was the result of provocation that was so
compelling that a reasonable person would act in a similar
manner under similar circumstances.
5. "Twinkle" defense: The California Supreme Court allowed
some mitigation of criminal responsibility after evidence was
introduced that ingesting an excessive amount of junk food
with high sugar content caused the defendant's behavior.
(The California legislature later repealed this as a defense.)
6. XYY defense: This plea involves a chromosomal abnormality
in men. The legal theory holds that the extra Y chromosome
produces abnormal aggression with poor impulse control. It
INTRODUCTION
is then argued that as a consequence of this defect, the
accused is legally insane. Psychologists rarely become in-
volved in this type of defense.
7. M'Naughton rule (insanity plea): The M'Naughton rule holds
that "The party accused was lacking 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, that
he did not know what he was doing was wrong"
(M'Naughton, 1843, p. 722). This rule is strictly a cognitive
standard of insanity and is called a "right and wrong" test.
It does not take into account the emotional aspects of behav-
ior and affective states.
8. Irresistible impulse (insanity plea): The irresistible impulse plea
means that the "reasoning powers [of the accused] were so
far dethroned by his diseased mental condition as to deprive
him of will power to resist the insane impulse to perpetuate
the deed, though knowing it would be wrong" (Smith v.
United States, 1929, pp. 548, 549). This plea adds a volitional
component to the cognitive component of the M'Naughton
standard. Irresistible impulse is extremely difficult to prove.
How does one differentiate between an irresistible impulse
and an unresisted impulse? At what point does a person
distinguish between choosing not to exert control versus
being unable to exert control? The courts have ruled that
the behavior falls under the definition of irresistible impulse
if the presence of a police officer would not be sufficient to
stop the behavior.
9. Durham rule (insanity plea): Durham v. United States (1954)
established that the accused is not criminally responsible if
his or her criminal activity was the product of a mental
disease or defect. Initially the word product was excessively
vague. Psychodynamic theory can argue that virtually any-
thing can cause anything else, and mental disease and defect
was also undefined and left up to the practitioner to define.
Subsequently, mental disease and defect was defined as "any
abnormal condition of the mind which substantially affects
mental and emotional processes or substantially impairs be-
havior controls" (McDonald v. United States, 1962). (This
standard has now been replaced by the American Law Insti-
tute standard—see below.)
10. Diminished capacity (insanity plea): Culpability requires one
to deliberate, premeditate, maturely and meaningfully reflect
upon one's act, harbor malice, and be able to form the neces-
10 PERSONALITY-GUIDED FORENSIC PSYCHOLOGY
sary intent (mens rea) to commit the crime. The diminished
capacity standard exculpates a defendant if, as a result of
mental disease or defect, a person lacks the requisite specific
intent to commit the alleged crime.
11. American Law Institute (ALl; insanity plea, articulated in the
Model Penal Code; ALl, 1962): "As a result of mental disease
or defect [the accused] lacks substantial capacity either to
appreciate the criminality [wrongfulness] of his conduct or
to conform his conduct to the requirements of law" (Sect.
4.01, p. 23). This standard excludes antisocial and psycho-
pathic abnormalities.
12. Federal Insanity Defense Reform Act (1984) (insanity plea):
"The defendant, as a result of severe mental disease or defect,
was unable to appreciate the nature and quality of the wrong-
fulness of the act" (as cited in American Bar Association,
1989, p. 20). Mental disease or defect and cognitive incapac-
ity are components of insanity standards across all juris-
dictions. Volitional incapacity and exclusion of antisocial
personality disorders vary in each state's insanity standard.
In most jurisdictions, personality disorders, substance abuse,
and disorders of impulse control (e.g., pyromania, gambling)
do not exculpate defendants.
13. Guilty but mentally ill (insanity plea): In this plea, defendants
are committed to a psychiatric hospital for treatment until
their mental illness is in remission. They are then transferred
from the hospital to a correctional facility to complete their
sentence. Their time in the hospital is credited toward their
prison sentence.
LEVELS OF PROOF
Psychologists have been trained to rely on probability theory to ascribe
a degree of certainty to a hypothesis. If the level of probability is .01, then
it is 99% probable that the results can be attributed to the variables under
investigation. In court, different standards of proof apply, depending on the
jurisdiction and the legal issue in question. These levels of proof are "beyond
a reasonable doubt," "clear and convincing evidence," and "preponderance
of evidence." The psychologist will be asked to render an opinion "to a
reasonable degree of certainty." This phrase does not apply to statistical
probability or to legal definitions of proof; it means that the psychologist
has ruled out other possible explanations and is reasonably confident that
the explanation given is the most likely one.
INTRODUCTION 11
DIFFERENCES BETWEEN CLINICAL AND FORENSIC PRACTICE
Forensic interviews differ from traditional clinical interviews in a num-
ber of significant ways. In treatment, psychologists usually adopt a supportive,
accepting, and empathic stance toward the patient, but the forensic psychol-
ogist must adopt a more investigative role while searching for truth. In
doing so, the forensic psychologist may act in a neutral, objective, and
detached manner (Greenberg & Shuman, 1997). There is sufficient evidence
to support the notion that litigating patients are prone to malinger, to
overreport symptoms, and to answer questions in ways that affect psychologi-
cal test scores. For example, patients injured in industrial accidents tend to
heal at certain rates, but compensation-seeking patients with the same
injuries may take longer to heal (see Williams, Lees-Haley, & Djanogly,
1999). Workplace injuries are more fully discussed in chapter 5.
The clinical psychologist's main goal is to help the client; the forensic
psychologist's main goal is to help the court. Clinical psychologists often
are required to make a psychiatric diagnosis, but the forensic psychologist
makes only those diagnoses that are incidental to the main issue in the
case. To the extent that the diagnosis is helpful to the court (i.e., psychotic
disorders in insanity pleas), forensic psychologists make such diagnoses. In
other cases (e.g., child custody evaluations, screening of law enforcement
applicants), diagnoses may not be warranted.
Whereas clinical psychologists may see the patient for multiple sessions
over an extended period of time and in less structured formats, the forensic
psychologist may see the patient only for a few sessions and, in some cases,
only once or twice and in highly structured formats. These different interview
conditions require a different way of thinking by the psychologist. For
example, if a patient has been deposed on several occasions about PTSD,
then prior exposure to the evaluation and questioning may help the patient
present a more realistic picture of the disorder to the next forensic psycholo-
gist at the next evaluation. Clinical psychologists rarely consider this, but
a forensic psychologist would have to explore for this possibility. As a
standard of proof for the veracity of a conclusion, clinical psychologists tend
to trust their clinical judgment, research psychologists rely on alpha levels,
and the forensic psychologist must follow the court dictates that require
"beyond a reasonable doubt," a "preponderance of evidence," or "clear and
convincing evidence."
Privilege is the right to protection of information given in the context
of a professional relationship from discovery in evidentiary proceedings.
Most work of the clinical psychologist is privileged information (unless the
client waives his or her right of privilege), whereas most forensic evaluations
have no such protection. In fact, forensic psychologists are ethically required
12 PERSONALITY-GUIDED FORENSIC PSYCHOLOGY
