In the case of Heien v. North Carolina, 2014, the US Supreme Court ruled that a police officer's reasonable mistake of law can provide individualized suspicion justifying a traffic stop under the Fourth Amendment. The case arose when Nicholas Brady Heien was stopped by a police officer for having one broken brake light, although North Carolina law requires only one working brake light. During this stop, the officer found and seized cocaine from Heien's vehicle. The court held in an 8-1 decision that because the officer's misunderstanding of state law regarding brake lights was reasonable, it did not violate Heien’s Fourth Amendment rights against unreasonable searches and seizures.

In the dissenting opinion for Heien v. North Carolina, Justice Sonia Sotomayor argued that allowing police to stop individuals based on a misunderstanding of the law contradicts Fourth Amendment protections against unreasonable searches and seizures. She contended that this ruling could lead to an erosion of civil liberties as it gives too much power to law enforcement officers who may not fully understand or correctly interpret the laws they are enforcing. Furthermore, she expressed concern about potential racial profiling implications and emphasized that ignorance of the law is no excuse for citizens; therefore, it should also apply to those in positions of authority such as police officers. In her view, permitting stops based on reasonable mistakes of law would mean further diminishing the Fourth Amendment's protection against arbitrary government interference.