The Fourth Amendment protects against unreasonable searches and seizures. What is required for a search to be 'reasonable'?

The Fourth Amendment's reasonableness requirement is primarily satisfied when a neutral judge issues a warrant based on probable cause, meaning there is a fair probability that evidence of a crime will be found in the specific place to be searched. Courts have carved out numerous warrant exceptions: consent (voluntarily agreeing to be searched), exigent circumstances (like hot pursuit or imminent destruction of evidence), plain view (contraband visible without a search), search incident to a lawful arrest (searching the person and immediate area upon arrest), and the automobile exception (probable cause to believe a vehicle contains evidence). The exclusionary rule generally prevents evidence obtained in violation of the Fourth Amendment from being used in court.