Academic journal article Washington and Lee Law Review

Violence Risk Assessment: Scientific Validity and Evidentiary Admissibility

Academic journal article Washington and Lee Law Review

Violence Risk Assessment: Scientific Validity and Evidentiary Admissibility

Article excerpt

I. Introduction

Violence risk assessment is a critical and expanding part of the practice of mental health law in the United States. "Dangerousness to others" first became one of the pivotal criteria for involuntary hospitalization of people with mental disorders in the 1960s.(1) Courts first imposed tort liability on

clinicians who negligently failed to predict their patients' violence in the 1970s.2 In the 1980s, many states statutes enacted statues authorizing involuntary tW&att in the community for otherwise "dangerous" patients.3 During the 1990s, the Americans with Disabilities Act (ADA)4 explicitly mandated risk assessments of violence.5

In Part II of this Article, I review existing research on the validity of clinical risk assessments of violent behavior. In Part III, I consider whether, in light of this research, clinical risk assessments of violence are admissible as scientific evidence.

II. Violence Risk Assessment: The State of the Sciencel

Since the publication by Paul Meehl of Clinical Versus Statistical Prediotion in 1954,7 it generally is accepted that there are two fundamental approaches to risk assessment. In Meehl's most recent account, he contrasted

two ways of forcasting behavior. One, a formal method, uses an equation, a formula, a graph, or an actuarial table to arrive at a probability, or expected value, of some outcome; the other method relies on as informal, "in the head," impressionistic, subjective conclusion, reached ... by a human clinical judge.8

The latter is called the clinical approach and the former the actuarial approach. I will consider each in turn.

A. Clinical Approaches to Risk Assessment

I reviewed research on the accuracy of clinical judgments at predicting the criterion of "violent behavior toward others" in 1981.9 The research concluded that "psychiatrists and psychologists are accurate in no more than one out of three predictions of violent behavior over a several-year period among institutionalized populations that had both committed violence in the past (and thus had high base rates for it) and who were diagnosed as mentally ill."10 Remarkably, only one study of the validity of clinicians at predicting "violence in the comunity" was published between 1979 and 1993.(11) This was a study of court-ordered pretrial mental health assessments conducted in 1978.(12) Consistent with the previous literature, 39% of the defendants rated by clinicians as having a "high" likelihood for being violent to others were reported to have committed dangerous acts during a two-year follow-up, compared to 26% of defendants considered as having a "low" likelihood, a statistically significant difference.13

In the last decade, researchers have shown a renewed interest in the topic of clinical risk assessment.14 For example, Lidz, Mulvey, and Gardner, in what

is surely the most sophisticated study published on the clinical prediction of violence, took as their subjects male and female patients being examined in the acute psychiatric emergency room of a large civil hospital. …

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