The entry of police officers or other law enforcement into a home without a warrant is valid under the United States Constitution under certain conditions. The following criteria must be met: 1) probable cause for the search, and (2) exigent circumstances that justify dispensing with the warrant requirement. If these criteria are not met, any evidence obtained will not be presented to the jury and will not be admissible at trial.
In the context of criminal procedure, exigent circumstances has been defined as those circumstances that would cause a reasonable person to believe that entry by the police without a warrant was necessary to prevent physical harm to the officers or other persons, the destruction of relevant evidence, the escape of the suspect, or some other consequence or circumstance that would improperly hinder legitimate law enforcement efforts.