Burden of Proof - Reasons For The Rule

In justifying its holding, the Winship Court invoked the two distinct functions that generally are attributed to the reasonable doubt rule. First, the rule is meant to reduce the likelihood of erroneously convicting an innocent defendant. It puts a thumb on the defendant's side of the scales of justice to implement "a fundamental value determination of our society that it is far worse to convict an innocent man than to let a guilty man go free" (Winship, p. 372, Justice Harlan concurring).

Second, the rule symbolizes for society the great significance of a criminal conviction by singling out criminal convictions as peculiarly serious among the adjudications made by courts. The rule reaffirms the special opprobrium that attaches to criminal convictions, and the special importance of protecting individuals against the state's power to convict.

There are, of course, empirical questions about whether the rule in practice has its intended effect. The available studies are inconclusive, but they suggest that the instruction on the burden of proof can affect the outcome of a case (L.S.E. Jury Project; Simon, 1969, 1970; Simon and Mahan).