Final answer:
Law enforcement officials usually need a warrant to perform searches and seizures, but there are exceptions such as with consent, under exigent circumstances, plain view, and search incident to arrest. Without a valid warrant or exception, any evidence obtained is subject to the exclusionary rule and may be inadmissible in court.
Step-by-step explanation:
Under the Fourth Amendment, law enforcement is generally required to obtain a warrant for searches and seizures. Warrants, which must be based on probable cause, are granted by a judge and specify what can be searched and what may be seized. However, there are exceptions to the warrant requirement including instances of consent, when evidence is in plain view, during exigent circumstances, and as a search incident to arrest.
For instance, if an individual gives consent to a search, a warrant is not needed. In exigent circumstances, such as when there is an immediate risk of evidence destruction or a threat to public safety, law enforcement can proceed without a warrant. Furthermore, if illegal items or evidence is in plain view of a government official who is lawfully present, that evidence can be seized without a warrant. Additionally, a search incident to a lawful arrest does not require a warrant.
In cases where an illegal search or seizure occurs without a warrant and without fitting any exceptions, the exclusionary rule mandates that such evidence cannot typically be used in court. This was affirmed by the Supreme Court in Mapp v. Ohio, which solidified the broad application of the exclusionary rule.