Timothy Sandefur argues that the phrase “due process of law” is a promise of regular, non-arbitrary treatment by the government. That promise certainly entails procedural elements, but we would be hard-pressed to justify any of them without reference to a deeper, implicit, and ultimately substantive guarantee. “Citizens are entitled to procedures only because they are entitled to lawful treatment,” Sandefur writes. Arbitrary, irrational, or merely self-serving government acts are not lawful acts, properly speaking, and they should be overturned on substantive grounds. The process of law that is due to citizens is more than just a ritual or a procedure; it also requires judges to ask whether the law serves public or merely private ends.

Professor Rosenthal sympathizes with the idea that the Constitution protects us against unjust majorities. But he holds that the Due Process clause does not act as Sandefur claims. “The First Amendment expressly limits the scope of legislative power,” he writes, “[but] the Due Process Clause does not.” Even were we to grant that laws must be in the service of a general, public principle, substantive due process wouldn’t necessarily yield the results we predict or desire. Instead, it would amount to an unreviewable judicial veto.

Ryan Williams argues that substantive due process is both an intelligible concept and also a part of American law. He argues, however, that it did not become a part of the federal Constitution until the ratification of the Fourteenth Amendment in 1868. Prior to that, public understandings of “due process of law” did not contain any reliable understanding of a check on the legislature, only on the executive and the courts. Substantive due process needs to be understood as a relatively recent historical development, though not by any means a bad one.

Gary S. Lawson agrees that the Constitution, even without the Fifth Amendment, seems to instantiate a rule against arbitrary conduct — for the federal government. The Fifth Amendment makes the matter more explicit. But does the Fourteenth Amendment do the same for the states? On this point, Lawson proposes several important doubts. Still, he argues, Sandefur has made a very strong case for a substantive element to due process.