Although the Supreme Court has historically resisted a partisan sorting out of its public legitimacy, today, Republicans and Democrats look at the Court in very different ways. This Element assembles original survey and experimental data to unpack these changes in three ways. First, the authors illustrate the powerful role that partisanship plays in shaping judicial public opinion. Second, they validate a new three-item measure of specific support and show that it reliably predicts perceptions of Supreme Court legitimacy. Finally, they introduce a new, applied measure of support for the rule of law and connect it to specific and diffuse support. Taken as a whole, their work demonstrates that large chunks of the mass public view the Supreme Court critically. Looking ahead, it is unclear whether legitimacy will rebound when citizens perceive that the balance of judicial power within the nation's High Court has fractured along party lines.