We know that a police officer must give the Miranda warning before interrogating someone who is in custody. If the officer doesn't, the suspect's statements—and evidence resulting from it—usually can't be used against the suspect at trial. (See Statements Obtained When Police Violate Miranda.)
But what if the officer knows the suspect just left a loaded gun at a busy playground? If the officer asks, "Where did you put the gun?" before reading the suspect her rights, will the suspect's reply or the gun be kept out of evidence? No. The public safety exception to the Miranda rules applies in situations like these. (Some may refer to it, or something extremely closely related to it, as The Emergency Exception to the Miranda Rule.)
In the seminal case of New York v. Quarles, the Supreme Court said that an officer's concern for public safety can justify a failure to give Miranda warnings. (467 U.S. 649 (1984).) In that case, a woman told police a man with a gun had just raped her. She also said the man entered a nearby store.
An officer spotted a man in the store matching the description the victim gave and ran after him. The officer caught him, noticed he was wearing an empty gun holster, and handcuffed him. Moments later, other officers arrived. The officer then asked the man where the gun was. The man nodded in a certain direction and said, "The gun is over there." The officer then retrieved it.
Miranda applied to this situation—the officer interrogated the man while he was in handcuffs and surrounded by four officers. (See Miranda: The Meaning of Custodial Interrogation.) But no one read the man his rights until after his statement.
So, when the defendant faced charges for illegal weapon possession, lower courts decided that the gun, and the man's statements about it, were inadmissible. But the U.S. Supreme Court disagreed, creating a public safety exception to the Miranda rule. The Court decided that Miranda doesn't apply to a situation where officers ask questions legitimately designed to protect their safety or that of the public.
Courts disagree on what constitutes a threat to public safety that triggers the public safety exception. Some say that the exception applies broadly in situations that are dangerous, even if the officer doesn't have knowledge of an actual threat—for example, when officers ask an in-custody suspect about possible weapons in his car without knowing about any missing weapons. Others apply it narrowly, saying that it's available only if the officer knows about an immediate threat—for instance, when an officer knows someone just placed a loaded weapon in a public area. (U.S. v. Liddell, 517 F.3d 1007 (8th Cir. 2008); U.S. v. Estrada, 430 F.3d 606 (2d Cir. 2005).)
The public safety exception most often applies in cases involving weapons or dangerous items. It may also operate where officers are trying to locate an armed accomplice or an injured person. The exception applies only if the officer's questions focus on the issue causing the safety concern, and if he didn't design them to elicit incriminating evidence.
Example: Dispatch calls an officer to a traffic accident and he finds a man standing over the body of a woman. The woman is lying on the ground with blood around her head. The officer asks what happened; the man says he accidentally shot her while she was driving. The officer handcuffs the man and makes him lie on the ground. The officer doesn't give a Miranda warning, but asks where the gun is. The man says he thinks it's in a nearby van. Two more officers arrive and ask about the gun. The suspect's responses to the questions about the gun fall within the public safety exception. But an officer subsequently asking the suspect "What happened?" violates Miranda because the officer knows the suspect, who is now in custody, has claimed that he accidentally shot the woman, and because the broad query isn't focused on the emergency situation. The suspect's response to this question doesn't fall within the public safety exception. (Bowling v. State, 717 S.E.2d 190 (Ga. 2011).)
Example: An officer makes a traffic stop of a known meth manufacturer. He arrests him, handcuffs him, and puts him in the patrol car. He doesn't read him his Miranda rights. The officer, who knows the suspect to be a meth cook and knows the volatility of meth-lab materials, needs to move the suspect's car. The officer asks if there is any meth or a small-batch meth lab in the car. The suspect tells him there isn't meth or a lab in the car, but that a bag in the car contains a can of ether and other materials. The public safety exception applies because the officer made a reasonable inquiry about a safety hazard. (U.S. v. Noonan, 745 F.3d 934 (8th Cir. 2014).)
Courts differ on how they apply the public safety exception, and the law may vary somewhat from one state to another, and between state and federal court. If you are facing criminal charges, an experienced criminal defense lawyer should be able to fully explain the law, protect your rights, and help you understand your options.