In 1874, the Supreme Court held in Murdock v City of Memphis that it lacked “jurisdiction” to review a state supreme court’s interpretation of state law, even in cases that present federal-law claims. The justices have since backed away from that seemingly ironclad rule; they now review and set aside state-court interpretations of state law that lack “fair and substantial” or “adequate” support in certain cases where the justices wish to enforce federal rights against the states. Yet the justices continue to labor under the Murdock-inspired notion that they are powerless even to consider reversing a state supreme court’s ruling solely on state-law grounds, as a means to avoid ruling on the federal-law claims presented in a case. This Article challenges the Court’s categorical unwillingness to consider such state-law reversals. First, there are no statutes or constitutional provisions that foreclose the Supreme Court from reversing a state supreme court’s judgment solely on state-law grounds, so long as the case presents a colorable federal-law claim sufficient to satisfy Article III and 28 USC § 1257. Second, the Supreme Court’s refusal to consider such state-law reversals is in tension with its oft-stated desire to avoid resolving federal constitutional issues unless absolutely necessary. When state supreme courts issue controversial interpretations of state law that simultaneously give rise to difficult constitutional questions, the Murdock regime forces the justices into a binary choice: allow such state-court judgments to stand, or reverse on federal constitutional grounds. When the justices are unwilling to affirm the state supreme court’s ruling, this false dichotomy causes them to issue unnecessary and often contentious pronouncements of federal constitutional law. These Murdock-induced constitutional pronouncements are often costly substitutes for state-law reversals. They produce nationalized, constitutionally entrenched holdings; this significantly increases the error costs of the Court’s ruling if the justices’ views turn out to be mistaken. In addition, the novel constitutional holdings that the Court has created in its efforts to counter what it perceives as pernicious state-court rulings threaten to impose large decision costs on future courts by complicating federal constitutional doctrines. The Supreme Court could mitigate or avoid these harms by recognizing an option to reverse certain state supreme court rulings on minimalist, state-law grounds; this will alleviate the hydraulic pressure that the Murdock regime imposes on federal constitutional doctrine.