While scholars have long probed the original understanding of judicial review and the early judicial review case law, this Article presents a study of the judicial review case law in the United States before Marbury v. Madison that is dramatically more complete than prior work and that challenges previous scholarship on the original understanding of judicial review on the two most critical dimensions: how well judicial review was established at the time of the Founding and when it was exercised. Where prior work argues that judicial review was rarely exercised before Marbury (or that it was created in Marbury), this Article shows that it was far more common than previously recognized: there are more than five times as many cases from the Early Republic as the leading historical account found. The Article further shows that all of the cases in which statutes were invalidated fell into three categories: courts invalidated statutes that affected the powers of courts or juries, and they did so even when the legislation could plausibly be squared with constitutional text and prior practice; state courts invalidated state statutes for inconsistency with the federal constitution; and federal courts invalidated state statutes, and, again, they did so even when the statutes could plausibly be defended as constitutional. Scholars have missed this structural pattern, and the dominant view has been that only clearly unconstitutional statutes were invalidated. The Article shows, instead, that the early case law reflects a structural approach to judicial review in which the level of scrutiny was closely linked to the nature of the challenged statute and that courts aggressively protected their power, the power of juries, and the power of the national government.