In this Article, I argue that the alleged incoherence and unpredictability of the dormant Commerce Clause doctrine (DCCD) is rooted in the Supreme Court's search, through the years, for a stable set of rules enabling it to distinguish permissible from impermissible state regulations of interstate commerce and commercial actors. Its lack of success, the Article argues, is due in large part to the Court's inability to settle on the constitutional command the doctrine was to enforce. Historically, the Court would promulgate a set of rules, apply them for a time, then alter or modify them as the rules became unsatisfactory. Recent cases with similar facts, yet producing different results, suggest that the superficial stability the Court has achieved with the DCCD in recent years is largely an illusion. Both the "antidiscrimination principle" and the so-called 'Pike balancing"-each representing one of the two tiers in the Court's standard of review--are experiencing the same decline and decay as prior rules regimes. Recent cases suggest that the Court appears poised once again to alter the DCCD but is proceeding in an undertheorized, ad hoc manner. Using the "constitutional decision rules" model of constitutional interpretation developed by Mitchell Berman, and influenced by doctrinal theorists like Richard Fallon and Kermit Roosevelt, I argue that the DCCD could be improved by settling on a "constitutional operative proposition" rooted in the text and history of the Constitution and the Commerce Clause, and devising "decision rules" that would implement that constitutional command. I conclude that the Framers centralized commercial regulation to prevent state regulations of interstate commerce likely to produce friction among states, incite retaliation, and undermine political union. I specifically reject any attempt to impute a free-trade ideology to the Framers. Decision rules enforcing the DCCD should, therefore, go no further than addressing the sorts of "discrimination" that produce this union-undermining effect. In particular, I would have the Court discard the "balancing" of burdens and benefits flowing from truly nondiscriminatory state and local laws. Applying the reconstructed decision rules to several difficult doctrinal areas, I argue, results in either a more satisfactory explanation for actions the Court has taken, or shows more clearly how the Court has incorrectly resolved particular issues.