This Article examines and questions the jurisprudence that turns a blind eye to evidence that the jury instruction presumption, the assumption that juries understand their instructions, is ill-founded. While the presumption applies in any jury trial, the Article emphasizes the particular injustice associated with is application in criminal cases. Evidentiary presumption bases upon anything less violates an accused’s right to due process of law. Therefore, it is particularly troubling that in criminal cases, the presumption regarding the efficacy of crucial jury instructions remain baseless.