The case is United States v. Caraballo, decided on August 1. Normally, the police have to get a warrant in order to search your person or your belongings. But the Supreme Court says a warrant is not needed if the police can prove "exigent circumstances," that is, an emergency that makes it impracticable to obtain a warrant. The officers did not think they had time to get a warrant to track the defendant through his cell phone, as they knew the victim was afraid of him and he was probably still running around with a gun and the residue from the shooting would dissipate if they waited too long to get the warrant. So they asked Sprint for his cell phone GPS information, and Sprint obliged. Through this expedited process, the police found the defendant and arrested him for murder.
The Court of Appeals (Calabresi, Lohier and Lynch) find that the police acted properly and did not need a warrant under the exigent circumstances doctrine, which applies under these circumstances:
(1) the gravity or violent nature of the offense with which the suspect is to be charged; (2) whether the suspect is reasonably believed to be armed; (3) a clear showing of probable cause . . . to believe that the suspect committed the crime; (4) strong reason to believe that the suspect is in the premises being entered; (5) a likelihood that the suspect will escape if not swiftly apprehended; and (6) the peaceful circumstances of the entry.
There was exigency here. This was a brutal killing and the officers had good reason to think defendant was armed. They also reasonably believed he was the primary suspect, as the victim had previously told the police she feared he might kill her if he knew she was speaking with the police. The officers also had reasons to think defendant would commit violent acts against law enforcement and confidential informants, as he told the victim he would kill her if she spoke to the police. And there was no time to get a warrant; while they waited for Sprint to respond to the warrant, defendant would kill someone. On top of that, the intrusion into defendant's privacy was relatively slight, and his expectation of privacy into his cell phone information was dubious, as the Supreme Court had not yet held that the warrantless access into cell phone information implicates the Fourth Amendment.