ABSTRACT :: Proof rules in law dictate when facts have been proven. They do so by specifying a level of proof such as by a preponderance of the evidence, by clear and convincing evidence, or beyond a reasonable doubt. The goals of the rules are to minimize errors (accuracy) and to allocate the risk of error fairly. I argue that the current rules fail to serve these two goals. Rather than suggesting we abandon these well- entrenched rules, I propose and argue for “second order” proof rules that will better align decision-making with its goals by providing criteria for applying the current rules. The second-order rules have the potential to improve not only factual decision-making at trial but also decisions implementing procedural rules that depend on judgments about the “sufficiency of the evidence.” These procedural rules include summary judgment and judgment as a matter of law in civil cases and sufficiency challenges by criminal defendants.