The Fourth Amendment–Free Zone in the United States
The federal government, mainly through Department of Homeland Security agencies like Immigration and Customs Enforcement and Customs and Border Protection, has vast authority to patrol the US border and interior to prevent the illegal entry of people and goods and enforce immigration law. That includes the power to conduct warrantless and suspicionless searches of vehicles within 100 miles of a US border. But the Fourth Amendment to the US Constitution protects people against unreasonable searches and seizures and requires warrants be issued only upon probable cause. A policy that permits warrantless searches risks violating these constitutional protections.