Petitioner William Case was charged with assaulting a police officer following a warrantless entry into his home. The incident began when Case's ex-girlfriend called 911, reporting that Case had threatened suicide, mentioned a suicide note, and made a sound resembling a gunshot before the line went dead. Police officers arrived at Case's home, observed an empty handgun holster and a notepad inside, and received no response to their knocking. Fearing Case had already shot himself or was about to do so, officers entered the home to render emergency aid. Inside, Case emerged from a closet holding an object that looked like a gun, leading an officer to shoot and injure him. Case moved to suppress the evidence, arguing the entry violated the Fourth Amendment. The Montana Supreme Court upheld the entry under the state's community caretaker doctrine, requiring only that an officer suspect a person is in peril based on specific and articulable facts, a standard the Court found too low for home entries.
Justice Kagan delivered the opinion of the Court, reaffirming the rule from Brigham City v. Stuart that the Fourth Amendment allows warrantless home entries when officers have an 'objectively reasonable basis for believing' that an occupant is seriously injured or imminently threatened with such injury. The Court addressed two primary legal questions. First, it clarified the applicable standard of proof. The Court rejected the petitioner's argument that the emergency aid exception requires 'probable cause,' noting that probable cause is peculiarly related to criminal investigations and would fit awkwardly in non-investigatory emergency scenarios. The Court also rejected the Montana Supreme Court's application of a 'reasonable suspicion' standard, which is appropriate for street stops but too low for the heightened privacy interests of the home. Instead, the Court held that the 'objectively reasonable basis' standard applies without further gloss. Second, the Court applied this standard to the facts. The officers possessed an objectively reasonable basis to believe Case needed emergency aid based on the 911 call describing a suicide threat and gunshot, the visual evidence of a suicide note and empty holster, and Case's history of mental health issues and prior suicide-by-cop attempts. The Court emphasized that the reasonableness of the entry is evaluated based on the totality of the circumstances at the time of the decision, not on whether the entry itself created a danger. The Court affirmed the judgment, noting that while the Montana court's reasoning was flawed, the result was correct.
This decision solidifies the 'objectively reasonable basis' standard as the exclusive test for warrantless home entries under the emergency aid exception, preventing lower courts from applying a lower 'reasonable suspicion' standard or a higher 'probable cause' standard. It clarifies that officers do not need probable cause to enter a home to save a life, but they must have a reasonable basis to believe serious harm is imminent. The ruling affirms the conviction in this case and provides guidance for law enforcement responding to mental health crises, emphasizing that the reasonableness of the entry depends on the specific facts known at the time, including the risk of suicide-by-cop, without requiring officers to wait indefinitely if there is a reasonable belief of immediate danger.