Supreme Court 4th Amendment Case
In Michigan v. Fisher, 130 S. Ct. 546, December 7, 2009, the U.S. Supreme Court held that law enforcement officers may enter a home without a warrant to render emergency assistance to an injured occupant or to protect an occupant from imminent injury.
The police officers in Fisher were responding to a report of a disturbance. When they arrived on the scene they encountered a tumultuous situation in the house--and they also found signs of a recent injury (drops of blood on the car and the walkway), perhaps from a car accident, outside. The officers could see violent behavior inside. The officers saw defendant screaming and throwing things. Although the man specifically denied the officers access and told them to go get a warrant, the Court held that it is objectively reasonable to believe that defendant's projectiles might have a human target (perhaps a spouse or a child), or that defendant would hurt himself in the course of his rage. The officer's entry was reasonable under the Fourth Amendment. See also Brigham City v. Stuart, 547 U. S. 398 (2006).
This reasoning, while completely justifiable in theory, could really lead down a really slippery slope in practicality. Just think how easy it will be for officers to simply barge into a home under the "protection from imminent injury" exception because they "heard a commotion." While that's not exactly what happened here, it could be where we end up soon.