This is the highest standard used as the burden of proof in common law countries. It usually only applies in criminal proceedings. If there is a real doubt, based upon reason and common sense after careful and impartial consideration of all the evidence (or lack of evidence) in a case, then the level of proof has not been met. If the jury, or judge in a bench trial, has no doubt as to the defendant's guilt, or if their only doubts are unreasonable doubts, then the prosecutor has proved the defendant is guilty.