Proof beyond a reasonable doubt has been de rigueur in criminal cases almost since the dawn of the republic. It is based on the premise that it is better to let several guilty people go free in order to save one innocent person from wrongful conviction. The jury in a criminal case is not merely an audience. It is the central mechanism without which the wheels of American criminal justice cannot turn-- and operates as the final safeguard against a grave error. However, while the Constitution describes the importance, composition, and role of the jury, it does not explicitly use the phrase “proof beyond a reasonable doubt.”
Though not mentioned in our founding document, proof beyond a reasonable doubt is “an ancient and honored aspect of our criminal justice system.” As such, this Article does not question its conceptual wisdom, but rather its jurisprudential implementation. Yet the meaning of “beyond a reasonable doubt” is apparently not self-evident. Jurors constantly ask for definitions of beyond a reasonable doubt. Some jurisdictions allow such a definition. Some require it. Others forbid it entirely under the supposition that its meaning is obvious and requires no definition. Juries are understandably curious and concerned about the meaning of “proof beyond a reasonable doubt.” They correctly assert to judges that it is not self-explanatory (despite many judges' erroneous insistence to the contrary). This creates real and significant risk the standard under which defendants are convicted is constitutionally inadequate. When jurors misapprehend how high the burden of proof beyond a *1030 reasonable doubt is, they are in danger of convicting the innocent, the gravest kind of mistake that is called “Type I error.” When they let a guilty person go free, they commit a less serious kind of mistake called “Type II error.” In fact, the theory behind proof beyond a reasonable doubt (letting several guilty people go free in order to save one innocent person) actually contemplates Type II error. The authors posit that many jurors simply don't understand how high a burden of proof beyond a reasonable doubt is supposed to be. They propose redefining proof beyond a reasonable doubt to make it more intelligible to the average juror. They realize the beyond a reasonable doubt standard is veritably sacrosanct in American law, but they don't believe “that's the way it's always been” is a good reason to perpetuate a standard of proof that is unintelligible to the average juror. They suggest changing the burden to a two-step analysis: (1) Did the prosecutor prove each and every element of the crime charged? (2) If so, keeping in mind the extraordinary injustice in the possibility of convicting an innocent person, are you convinced to a moral certainty? The authors are convinced that if American law can somehow let go of its “beyond a reasonable doubt” tradition, the incidence of grievous Type I error will be much lower.

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