So-called “substantive due process” has long been criticized progressives and conservatives as a contradictory interpretation of the Due Process Clauses, and one that undermines the popular sovereignty of We the People to govern themselves. In this Foreword, I explain why an individual conception of We the People, leads to a “republican” conception of popular sovereignty that requires a neutral magistrate to adjudicate whether a statute restricting the liberties of the We the People is within the just powers of a legislature to enact. Because a measure that is ultra vires is not truly “a law,” enforcing it against a fellow citizen and joint sovereign so as to deprive that person of his or her “life, liberty or property” violates what should be called the Due Process of Law Clauses. While the proper ends of Congress’s powers are enumerated in the text of the Constitution, the police powers of the states are more general. Still, the exercise of such powers to restrict the privileges or immunities of citizens in an “irrational or arbitrary” manner is beyond the just powers that a sovereign people can be presumed or supposed to have delegated to their servants in the legislature. Courts, who are also servants of the We the People, readily perform this type of evaluation when a “fundamental right” or “suspect class” is affected by the exercise of the police power, so such judicial engagement is well within their competence.