Sex offender registration and notification (SORN) laws have been in effect nationwide since the 1990s, and publicly available registries today contain information on hundreds of thousands of individuals. To date, most courts, including the Supreme Court in 2003, have concluded that the laws are regulatory, not punitive, in nature, allowing them to be applied retroactively consistent with the Ex Post Facto Clause. Recently, however, several state supreme courts, as well as the Sixth Circuit Court of Appeals, addressing challenges lodged against new-generation SORN laws of a considerably more onerous and expansive character, have granted relief, concluding that the laws are punitive in effect. This symposium contribution examines these decisions, which are distinct not only for their results, but also for the courts’ decidedly more critical scrutiny of the justifications, purposes, and efficacy of SORN laws. The implications of the latter development in particular could well lay the groundwork for a broader challenge against the laws, including one sounding in substantive due process, which unlike ex post facto-based litigation would affect the viability of SORN vis-à-vis current and future potential registrants.