Legal proceedings often involve multiple stages: U.S. civil litigation allows motions to dismiss and for summary judgment before reaching a trial; government agencies as well as prosecutors employ investigative and screening processes before initiating formal adjudication; and many Continental tribunals move forward sequentially. Decisionmaking criteria have proved controversial, as indicated by reactions to the Supreme Court’s recent decisions in Twombly and Lqbal and its 1986 summary judgment trilogy, which together implicate the four Supreme Court cases most cited by federal courts. Neither jurists nor commentators have articulated coherent, noncircular legal standards, and no attempt has been made to examine systematically how decisions at different procedural stages should ideally be made in light of the legal system’s objectives. This Article presents a foundational analysis of the subject. The investigation illuminates central elements of legal system design, recasts existing debates about decision standards, identifies pathways for reform, and provides new perspectives on the nature of facts and evidence and on the relationship between substantive and procedural law.