Highest burden of proof in a criminal case, placed normally on the prosecution. Because under common law the defendant is presumed innocent, his or her guilt must be proven to the entire satisfaction of the judge or jury. This term, however, does not imply 'beyond a shadow of a doubt.' If the evidence is so strong that there is only a remote possibility (and no probability) of an extenuating circumstance, the guilt is then deemed to have been proven beyond a reasonable doubt. Whether the same level of proof is required also in civil cases is still a matter of debate.