The E-Treatise details the usual doctrinal areas of constitutional law with copious supporting scholarship, but extends beyond doctrine to present the unique theme that American constitutional law can be divided into five eras characterized by distinctively different decisionmaking styles used by the decisive Justices (original natural law, formalist, Holmesian, instrumentalist, and modern natural law). Differences in decisionmaking style affect the choice and weight given to the various sources for interpretation: text; context; history; legislative, executive, and social practices; judicial precedents; and prudential considerations. Further, the Justices have had different style related predispositions regarding structural issues such as states’ rights, perceptions on executive versus legislative powers, and preferences on economic versus civil and political rights. The E-Treatise goes on to describe systematic differences in how different interpretation styles reason in terms of deduction versus induction, use of categorical versus balancing tests, doctrine phrased as elements to meet or factors to weigh, doctrine phrased as rules or standards, and whether any particular decision is a question of law rather than a question of fact. The E-Treatise identifies Justices who use the various styles, but goes beyond composition of the Court to describe political and social events that have influenced the Court’s composition and reasoning of the Justices during each era.