In the case of United States v. Cooley, 2020, Joshua James Cooley was stopped by a Crow Tribe police officer in Montana for being parked on the side of U.S Route 212 within the boundaries of the reservation. The officer noticed that Mr. Cooley seemed to be non-native and appeared to have watery and bloodshot eyes. Upon further investigation, methamphetamine and firearms were found in his vehicle leading to federal drug and gun charges against him. Cooley moved to suppress evidence arguing that tribal police lacked authority over non-Indigenous people on public roads within reservations under existing law which limits tribes' inherent sovereign power unless authorized by Congress or necessary for self-government. The District Court agreed with Mr.Cooley's argument stating that tribal officers could only stop or detain apparent non-natives if an obvious violation of state or federal law is evident before any interaction takes place between them; thus suppressing all evidence obtained during this encounter as it violated Fourth Amendment rights against unreasonable searches/seizures. However, upon appeal from government prosecutors, Supreme Court unanimously reversed this decision ruling that tribal officers can temporarily detain/search non-Native Americans traveling through their territory based on potential violations of state/federal laws while waiting for other authorities.

In the United States v. Cooley case, there was no dissenting opinion as the decision was unanimous. The Supreme Court ruled 9-0 in favor of Joshua James Cooley, a non-Native American who had been charged with drug and gun offenses after being searched by a tribal police officer on a federal highway within reservation boundaries. The court held that tribal police officers have authority to detain temporarily and search non-Native Americans traveling on public rights-of-way through reservations for potential violations of state or federal law.