Fourth Amendment law has developed almost entirely through the lens of urban policing. This Article identifies and critiques a parallel body of constitutional law that governs searches and seizures by conservation law enforcement officers in forests, waterways, and public lands. It calls this law the Green Fourth Amendment and describes the distinct set of statutory authorizations and judicial doctrines that comprise it.

Drawing on an original empirical analysis of more than 300 state and federal court decisions and a comprehensive survey of statutes from all fifty states, this Article maps how foundational Fourth Amendment doctrine operates differently when conservation law enforcement is at stake. It shows that courts have applied the open fields doctrine to extinguish privacy interests across vast categories of land, treated participation in a licensed recreational activity as blanket consent to warrantless inspection, approved roving suspicionless stops, and endorsed a form of “sportsman profiling” that permits stops based on appearance and location rather than individualized suspicion of wrongdoing.

Although conservation police work in a unique context, doctrinal erosion has consequences far beyond the conservation law enforcement context. This Article argues that weakened Fourth Amendment constraints migrate into traditional policing through interagency partnerships and doctrinal precedent and could extend to any licensed or regulated activity. The Green Fourth Amendment further destabilizes principles that structure existing constitutional criminal procedure— including the prohibition on suspicionless stops, the distinction between administrative and criminal searches, and the requirement that asserted government interests receive genuine rather than reflexive judicial scrutiny. By identifying and mapping the Green Fourth Amendment, this Article raises fundamental questions for criminal procedure about the scope of the reasonableness inquiry, the coherence of the administrative search and special needs exceptions to the warrant requirement, and the role of place and activity in defining constitutional protection.