Three Difficulties With Using State Constitutional Rights to Infer Federal Constitutional Rights:
I really appreciate Eugene's thoughtful response to my earlier questions about the relevance of state constitutional rights to whether courts should infer or an analogous federal constitutional right. At the same time, I'm not yet persuaded. Here's why:

  First, I have concerns with Eugene's approach from the standpoint of constitutional fidelity. I fear that looking to state constitutional provisions for new federal constitutional rights risks nullifying the decisions that Congress and the ratifying states actually made in amending the Constitution under Article V. As I understand it, the first Congress that debated and enacted the Bill of Rights looked largely to the provisions found in then-existing state constitutions for ideas. They selected the state constitutional amendments they wanted, and they declined to pick others.

  It seems to me that Eugene's proposed methodology risks effectively nullifying those decisions. It seems a bit like a constitutional version of "heads I win, tails you lose." Those state constitutional provisions actually adopted become part of the federal constitution, and those that weren't adopted become of the federal constitution anyway because they are "traditional" (at least if they are sufficiently common in the states). I would prefer a constitutional methodology that draws a sharper line between Constitutional amendments that were actually adopted and those that weren't.

  Second, I think Eugene's approach has troubling implications for federalism. If surveying state constitutions means that minority approaches tend to become constitutionally forbidden, you cause a shift in power from the states to the federal government. Diversity among the states is replaced by a one-size-fits-all rule from Washington, DC. This does happen in the Eighth Amendment setting, granted, but at least there's a textual hook: the word "unusual" suggests an inquiry into relative frequency, and state laws could help shed light on that. But here we seem to be interpreting no particular text at all, and the federalism concerns strike me as troublesome.

  Finally, the relevance of state constitutional practice seems at best modest under existing law. I agree with Eugene that legal history and tradition is often an important part of constitutional decisionmaking. But I think the role of state law in interpreting unenumerated rights is narrower than Eugene suggests. In the substantive due process context, for example, cases like Washington v. Glucksberg that have tried to root substantive due process in historical practice treat history as a necessary condition but certainly not a sufficient one. That is, newfangled rights don't get recognized, but the fact that a right has a long historical pedigree does not mean that it gets constitutionalized. Indeed, the same cases that try to root the doctrine in history warn that courts must be "reluctant" to expand substantive due process, "lest the liberty protected by the Due Process Clause be subtly transformed into the policy preferences of the members of this Court." Glucksberg.