This Article introduces the theory of post-supremacy federalism to describe a structural condition in which federal law remains formally binding, but enforcement has durably receded or collapsed. Unlike frameworks grounded in intergovernmental friction or negotiated cooperation, this account begins from federal retreat—the cumulative erosion of enforcement capacity across judicial, administrative, legislative, and executive institutions. Post-supremacy federalism arises when three conditions are met: (1) federal law remains intact; (2) enforcement retreats; and (3) no formal devolution occurs. In this vacuum, states are not merely filling gaps. They are governing by default—under laws that still bind but no longer structure governance in a coherent or consistent way.

This Article maps the institutional dynamics behind this transformation, including judicial realignment, administrative collapse, legislative paralysis, and the rise of executive unilateralism. It then traces how this retreat manifests in four domains: drug policy, public education, environmental protection, and reproductive healthcare. In each, federal authority persists in theory, but meaningful enforcement has eroded—leaving states to construct and implement their own legal regimes without delegation, partnership, or protection. These domains are not newly decentralized. They are abandoned. Statutes like the Controlled Substances Act, Title IX, the Clean Air Act, and EMTALA remain binding, yet no longer coordinate or constrain state action. In their place, states exercise contingent authority—governing under conditions of legal precarity and enforcement asymmetry, exposed to federal snapback and forced to navigate an unstable landscape.

This Article does not propose reform. It offers a diagnosis. Post-supremacy federalism names the legal condition that emerges when federal authority recedes but does not relinquish control. Naming that condition is the first step toward understanding how governance now unfolds—and what may come next.

In Catholic Charities Bureau v. Wisconsin Labor & Industry Review Commission, the Supreme Court unanimously struck down Wisconsin's test for religious exemptions from unemployment compensation, holding that conditioning exemptions on proselytization or service to co-religionists constitutes denominational discrimination. While the decision correctly identifies what states cannot do, it leaves unresolved what constitutional alternatives remain. This Article proposes the Sincerity-Then-Standards framework: courts should first presume the sincerity of an organization's religious self-identification absent evidence of fraud, then apply neutral, conduct-based standards focused on what the organization does rather than why. Drawing on analogies from the church-status presumption under I.R.C. § 508(c)(1)(A) and the Unrelated Business Income Tax, the framework avoids theological entanglement while offering a model for conduct-based regulation that may extend beyond the employment tax context.

Psychedelics are psychoactive sacraments (also known as entheogens) as well as medicines and recreational drugs. In the last few years, these substances have begun to be deprioritized, decriminalized, and legalized at the state and local levels. Some are also in the process of becoming FDA approved to be prescribed as part of psychedelic assisted psychotherapies. At the same time, the religious use of these substances, rooted in history, is becoming more destigmatized and religious organizations are increasingly willing to out themselves and engage with federal agencies related to their use of illegal drugs in a variety of ways. As a Graduate Tax Scholar at Georgetown University Law Center, I conducted research on approaches that these religious communities are taking with respect to their federal tax status. The key takeaway from that preliminary research was that due to these legal and cultural shifts, the number of religious communities utilizing psychedelics is significant and growing. From the perspective of the Drug Enforcement Administration (DEA), and the federal government, the religious use of psychedelics remains criminal absent a religious exemption. In response to a Supreme Court case in 2006, the DEA developed a constitutionally questionable religious exemption application process but has never voluntarily granted an exemption. Although there are a growing number of communities, many of which the government is fully aware of, only three communities currently have court ordered federal exemptions. The result of this is a lack of criminal law enforcement further frustrated by the religious freedom protections granted in the U.S. Constitution. This Article describes this current legal landscape at the federal, state, and local levels, how we got here, and importantly, the impact of the current policy of nonenforcement on public safety. In conclusion, this Article proposes two possible policy solutions to shift the legal landscape from legal defensibility into legal protection, increasing safety for all involved and reducing unnecessary burdens on government agencies.