What protections do criminal defendants have against unreasonable searches and seizures?

In the United States, criminal defendants are protected against unreasonable searches and seizures by the Fourth Amendment to the Constitution. This amendment mandates that, generally, law enforcement must obtain a warrant issued by a judge upon a showing of probable cause, supported by oath or affirmation, and specifically describing the place to be searched and the items to be seized.12

While the warrant requirement is the standard, the courts recognize several exceptions, such as searches incidental to a valid arrest, searches conducted with consent, and "stop and frisk" procedures where an officer has reasonable grounds to believe a person is armed and dangerous.1

To enforce these protections, the exclusionary rule prohibits the use of evidence obtained in violation of the Fourth Amendment in criminal proceedings. Established universally for all U.S. courts in Mapp v. Ohio (1961), this rule ensures that constitutional rights are upheld, though exceptions exist, such as evidence obtained by police in "good faith" reliance on a warrant later found to be invalid.312