In this essay, I intend to advance two primary ideas. In the first part, I argue that originalism, as a judicial philosophy incubated as a conservative reaction against the legislative excesses of the Warren Court, is intrinsically wedded to two core theses: (a) the (in principle) determinacy of legal rules and (b) judicial supremacy. By the ‘determinacy of legal rules,’ I mean the idea that, in all but borderline cases, a uniquely correct outcome can be determined, based on objective criteria, given the case’s facts and the legal principles most appropriately tied to those facts. This is the jurisprudential theory of legal positivism, which originalists [almost?] categorically accept. By judicial supremacy, I mean acceptance of the principle that the final interpretive authority of the Constitution is and should be the judiciary, as opposed to some other institutional actor. While generalizing about ‘originalism’ is dangerous, given the perhaps dozens of distinct varieties pursued by American legal scholars and jurists over the past half-century, I believe that these two ideas are intrinsic to most, if not all, strands of originalism widely utilized in the legal academy. Casting doubt on these theses would thus be a substantial contribution to contemporary debates over how the constitution should be interpreted. Primarily for their importance and familiarity to academic audiences, I focus on what I call two ‘old’ originalist jurists, Robert Bork and Antonin Scalia, and arguably the most central figure of ‘new’ originalist thought, Randy Barnett, to show how these two theses play into their versions of originalism. In the second part of this essay, I argue that the first of these ideas, the determinacy of law, is unappealing because legal rules themselves are often not sufficiently outcome determinative to fulfill the role that originalists tend to presume that constitutional rules, properly understood, should. My argument utilizes the interpretivist jurisprudence of Ronald Dworkin. If I am right, the question of who has interpretive authority is just as crucial as the question of how the Constitution should be interpreted. With regard to the second thesis, I argue that judicial supremacy is an inappropriate structural feature in our separation of powers system. Relying on the constitutional theory of German jurist Carl Schmitt, I argue, first, that the Supreme Court has generally proven incapable of serving, at least in times of crisis in which it is arguably most needed, as an efficacious guardian of constitutional norms, and, second, that its attempts to do so have proven disastrous for the legitimacy of the federal judiciary over the past few decades. I conclude with some normative arguments, based on the work of Jeremy Waldron, as to why the judiciary is an inappropriate institutional actor for the application of originalist methodology.