History

• The concept of what today is known as "reasonable doubt" originated in medieval Britain. With that noted, the reality was that the term had the opposite meaning of its definition today. In other words, when the concept of reasonable doubt was first introduced, it meant that a juror was obliged to convict a defendant even if he (all jurors were male) harbored a reasonable doubt as to the defendant's potential innocence.
  
  

Mind of a Reasonable Person

• Oftentimes there is confusion surrounding the burden or standard of reasonable doubt. The burden of proof beyond a reasonable doubt is the highest evidentiary standard in the U.S. and similar judicial systems. However, reasonable doubt does not mean no doubt whatsoever. Rather, in the mind of reasonable person there can be no plausible, alternative explanation for the facts and circumstances of the case and crime for which the defendant is charged.
  
  

Criminal Trials

• There is only one arena in the U.S. justice system (and in the judicial systems in many other countries the world over, including the U.K., Canada and Australia) in which the burden of proof of beyond a reasonable doubt is used: criminal trials. Only during the actual trial of a criminal case does the jury have the responsibility of rendering its verdict beyond a reasonable doubt.
  
  

Grand Juries, Preliminary Hearings

• Reasonable doubt is not required during the preliminary stages of a criminal proceeding. For example, when an initial determination is made as to whether a criminal case should proceed, the standard used by the judge or grand jury is probably cause. In other words, there is a reasonable likelihood that a crime has been committed and that the person charged with the crime is the individual at fault.
  
  

Civil Trials

• Civil trials utilize a completely different standard of proof, reasonable doubt never coming into play in these types of proceedings. In civil trials, the standard is preponderance of the evidence (or, in some jurisdictions, clear and convincing evidence). As opposed to beyond a reasonable doubt, this means that there is a greater than 50 percent chance that a particular position is true (even if only slightly).
  
  

Judge or Jury

• Most criminal trials have both a judge and a jury. When that occurs, the jury applies the beyond a reasonable doubt standard in making its determination regarding guilt. Although a criminal defendant has an absolute right to a trial by jury, he or she can elect (at his or her option) to have a "trial to the court." In such a situation, the judge also "serves as the jury." In that situation, the judge is obliged to apply the beyond a reasonable doubt standard when reaching a verdict.
  
  

Expert Insights

• Criminal trials of significant charges normally are tried before juries of 12 men and women. (In some minor criminal cases, some jurisdictions do allow smaller juries in limited situations.) Ultimately, all the defense needs to accomplish in order to prevent an adverse verdict in a trial is to leave one juror with reasonable doubt that the defendant is guilty as charged.