It is a bedrock principle of criminal law that the state must prove all elements of a crime beyond a reasonable doubt to obtain a conviction and deprive an individual of his liberty. This high burden of proof is generally considered to be a reflection of the famous Blackstone formulation that it is better for the law to incorrectly release ten guilty men than convict one innocent man.
Despite the endurance of this acceptable ratio of ten false negatives to one false positive in the criminal law, the Supreme Court has never formulated a similar “Blackstone ratio” for the law of civil commitment. Civil commitment is a form of preventive detention, which is often defined as the state’s confinement of an individual without a criminal conviction because it fears he may hurt himself or others. For over thirty years, the Court has held that the state cannot deprive a mentally ill individual of his liberty through civil commitment unless it proved with clear and convincing evidence that he was both mentally ill and dangerous. And for over thirty years, the Court has consistently refused to define the term dangerous. This refusal has produced a string of confusing Supreme Court opinions in recent decades that has resulted in gradual expansion of preventive detention, especially for the mentally ill, without any discussion of the accompanying normative costs.
This Note will explain why the Court should define danger, analyzing the Court’s decisions on civil commitment and preventive detention as well as recent psychiatric research on mental illness and violence risk assessment. This Note argues that the Court needs to address the costs of preventive detention by crafting a definition of danger that takes two factors into account: the likelihood of a potential harm and the seriousness of a potential harm. This definition will help legislators determine whether the costs of a preventive-detention scheme outweigh the benefits. This Note concludes by suggesting that a preventive-detention scheme should be upheld only where, at a minimum, its estimated benefits outweigh its estimated costs.
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