The approaching 75th anniversary of Erie v. Tompkins permits a critical reassessment of Justice Brandeis’s landmark opinion. This article joins the growing body of critical academic literature, focusing on the implausibility of the claimed reasons for overturning Swift v. Tyson. Erie’s claim to safeguard a constitutional place for state law rings hollow when seen in historic perspective, especially if one looks at the underlying question of the role of common law tort claims to control railroad accidents. While the doctrinal claims of Erie may not hold up, the concern about the regulatory consequences of federal court prohibitory injunctions continues to resonate. The article tries to resuscitate this aspect of Erie, perhaps best understood as the Progressive response to the perceived excesses of the Lochner period. Read this way, the concerns of Erie continue to manifest themselves in current controversies over claims of implied preemption, despite the doctrinal distance from the actual doctrinal claims of Erie itself.