Hastings Law Journal


In civil commitments, courts face the task of predicting the dangerousness of a mentally ill person and often turn to experts for help. Recently, the reliability of expert predictive testimony has improved; yet the best predictions still fall far short of reasonable certainty. Predictive science itself remains under scrutiny and is the subject of extended research and debate.

The modern handling of expert testimony, initiated in Daubert v. Merrell Dow Pharmaceuticals, Inc., might suggest that courts should exclude such unreliable expertise. The Daubert rules seem to imply a reliability standard under which trial courts should exclude expertise that lacks scientific validity. Such a test should require the exclusion of predictive expertise.

Yet no appellate court has ever done so; this Article assesses why. This Article reviews Daubert and its progeny, describes the science of prediction, and analyzes how predictive uncertainty affects and interacts with civil commitment law. It analyzes judicial decisions on the admissibility of predictions under both Daubert and the alternate Frye standard.

From this review, a more complex view of Daubert emerges. Instead of a test of scientific reliability, Daubert requires courts to weigh the reliability of expertise against its "fit" to the demands of a given case. Courts may admit even such deeply unreliable expertise as predictive testimony where it bears a sufficiently strong fit to the needs of the case. This Article proposes a methodology and an analytical structure with which to assess fit under Daubert, and suggests further directions for both doctrinal and theoretical development of the standard.

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