Why Beyond a Reasonable Doubt?

Scholars debate where the concept of guilt beyond a reasonable doubt originated from 18th-century lawyers in England, 16th Century theologians in Spain, 17th-century scholars of science in England, or from the Boston Massacre in 1770. Despite this historical controversy, United States Supreme Court Justice John Marshal Harlan II, considered a conservative member of the Warren Court, captured the essence of the reasonable doubt standard just a year before his death in his concurring opinion in In Re Winship, 397 U.S. 358 (1970), where he wrote that the due process clause of the U.S. Constitution expressly requires a reasonable doubt standard in a criminal case:

In a civil suit between two private parties for money damages, for example, we view it as no more serious in general for there to be an erroneous verdict in the defendant’s favor than for there to be an erroneous verdict in the plaintiff’s favor. A preponderance of the evidence [or more likely than not; more than 50% of the evidence] standard therefore seems peculiarly appropriate for, as explained most sensibly, it simply requires the trier of fact “to believe that the existence of a fact is more probable than its nonexistence before [he] may find in favor of the party who has the burden to persuade the [judge] of the fact’s existence.” Id at 371-372.

In a criminal case, on the other hand, we do not view the social dis-utility of convicting an innocent man as equivalent to the disutility of acquitting someone guilty. As MR. JUSTICE BRENNAN wrote for the Court in Speiser v. Randall, 357 U. S. 513, 525-526 (1958):

“There is always in litigation a margin of error, representing error in fact[-]finding, which both parties must take into account. Where one party has at stake an interest of transcending value—as a criminal defendant his liberty—this margin of error is reduced as to him by the process of placing on the other party the burden . . . of persuading the factfinder at the conclusion of the trial of his guilt beyond a reasonable doubt.”