Final answer:
Police may search without probable cause under 'exigent circumstances' when immediate action is necessary to prevent harm or destruction of evidence, despite the general requirement for a search warrant based on probable cause.
Step-by-step explanation:
The right of police to search without probable cause when failure to do so threatens the public is called exigent circumstances. Typically, the Fourth Amendment protects against unreasonable searches and seizures and requires a search warrant based on probable cause. Nonetheless, the law recognizes that there are emergency situations where acquiring a warrant is impractical, and immediate action is necessary to prevent harm to individuals or destruction of evidence. In such scenarios, law enforcement officers may conduct a search without a warrant under the principles of exigent circumstances.