Professors Richard Hasen and John Matsusaka, experts in election law and direct democracy, are skeptical of our approach. We appreciate their thoughtful comments, which have contributed helpfully to the debate. However, we think their skepticism misses the mark. They seem to confuse opposition to the single subject rule itself with opposition to our test.

Voters in many states use ballot propositions to enact laws on everything from term limits and abortion to taxes and same-sex marriage. Many of these propositions test the boundaries of federal and state constitutional law. This pits the people, who support the propositions and who are sovereign, against the parchment, which derives authority from ratification by people who came before. Judges, some elected, mediate this conflict by interpreting vague constitutional language. These ingredients make judicial review of propositions explosive. The practice exposes fundamental tensions in American law, including conflicts over when minority rights should yield to majorities, the reach of judicial review, and the optimal level of judicial independence.

In Direct Democracy and the Courts, Ken Miller, a political scientist and lawyer at Claremont McKenna College, makes an important and impressive contribution to scholarship in this field. The book blends history, institutional analysis, case law, and comprehensive data to tell the story of propositions, courts, and the constitutions that bind them. Miller does not advance a theory but instead explores a theme: the relationship between the initiative process and the judiciary. Sometimes that relationship has been contentious, manifesting the conflict between popular sovereignty and the judiciary that has simmered since the founding. Other times the relationship has been harmonious. Miller describes the times, places, and manners in which that relationship has developed.

Logic and language cannot yield a precise definition of “subject.” Instead, the definition must flow from citizens’ preferences and the democratic political process. Separability of issues in the minds of most voters implies an obligation to separate on the ballot, and inseparability implies permission to combine on the ballot. When a plaintiff contends that an initiative contains two subjects, the court should ask whether the majority of voters’ support for the first component hinges on whether the second becomes law. If the answer is “no,” then most voters can make their choice on each component separately. Consequently, the court should find that the initiative contains two subjects. Conversely, if the answer is “yes,” then most voters need to decide on both components simultaneously, and the court should find that the initiative contains one subject. The democratic process test increases citizens’ choices, just as direct democracy was designed to do, and preserves the legislature’s exclusive power to bundle issues and roll logs.