Reasonable doubt

Beyond (a) reasonable doubt is a legal standard of proof required to validate a criminal conviction in most adversarial legal systems. It is a higher standard of proof than the standard of balance of probabilities (US English: preponderance of the evidence) commonly used in civil cases because the stakes are much higher in a criminal case: a person found guilty can be deprived of liberty, or in extreme cases, life, as well as suffering the collateral consequences and social stigma attached to a conviction. The prosecution is tasked with providing evidence that establishes guilt beyond a reasonable doubt in order to get a conviction; albeit prosecution may fail to complete such task, the trier-of-fact's acceptance that guilt has been proven beyond a reasonable doubt will in theory lead to conviction of the defendant. A failure for the trier-of-fact to accept that the standard of proof of guilt beyond a reasonable doubt has been met thus entitles the accused to an acquittal. This standard of proof is widely accepted in many criminal justice systems, and its origin can be traced to Blackstone's ratio, "It is better that ten guilty persons escape than that one innocent suffer." Because a defendant is presumed to be innocent, the prosecution has the burden of proving the defendant's guilt on every element of each criminal charge beyond a reasonable doubt. To do so, the prosecution must present compelling evidence that leaves little real doubt in the mind of the trier of fact (the judge or jury) that the defendant is almost certainly guilty. For any reasonable doubt to exist, it must come from insufficient evidence, or conflicts within the evidence, that would leave an impartial factfinder less than fully convinced of the defendant's guilt. Accordingly, the standard of proof forces the factfinder to ignore unreasonable doubts—doubts that are frivolous, hypothetical, or not logically linked to the evidence—and to consider evidence favoring the accused, since reasonable doubt entitles them to an acquittal.