Beyond The Shadow of A Doubt

Beyond the shadow of a doubt, or beyond a shadow of a doubt, is a standard of proof. The phrase means the issue in question is so obvious, or has been so thoroughly proven, that there can exist no doubt. Two possible interpretations of "Beyond a shadow" might refer, first, to the fact that doubt could be nowhere in the vicinity (completely expelled from the issue), or second, to the thoroughness of the argument (a shadow being even less substantial than a doubt itself).