The Supreme Court
Police must follow strict rules for collecting evidence in order to be certain not to overstep the bounds of a person's Fourth Amendment rights. Many recent challenges to evidence-collection methods derive from search and seizure techniques police used as part of the war on drugs.
Most commonly these questions arose when police were doing checks of all cars or on buses for illegal contraband, weapons, or drugs. Do you know when you are allowed to refuse a search and what rights you give up once agreeing to a search? I'll answer those questions in this section using some recent court cases.