In a decision issued today in United States v. Caraballo, the U.S. Court of Appeals for the Second Circuit (per Judge Guido Calabresi) held that police did not violate the Fourth Amendment when they “pinged” a suspect’s cellphone because exigent circumstances existed. I find the outcome plausible on its facts, but the analysis strikes me as pretty unusual. Here are the details:

Frank Caraballo was a known drug dealer who was under investigation by narcotics officers. A woman who was an associate of his was found slain in an apparent execution-style killing. There was some reason to suspect that Caraballo was behind the killing. Two months earlier, the woman had told the police that she sold drugs with Caraballo and that he would “kill her” if he knew she was speaking to them. The police knew Caraballo’s cellphone number, so they asked the carrier, Sprint, to “ping” the phone. Pinging a phone sends a request for information to the GPS on the phone. The GPS returns the location within a range of 8 to 46 meters. As I read the opinion, the officers made the request four to five hours after the woman’s body was discovered.

Sprint had the officers fill out an exigency request form, presumably to satisfy 18 U.S.C. 2702(c)(4), which allows the disclosure of non-content information about a cellphone account “to a governmental entity, if the provider, in good faith, believes that an emergency involving danger of death or serious physical injury to any person requires disclosure without delay of information relating to the emergency[.]” The officers said that the reason for the emergency was “[m]ale with phones is suspect in possible homicide.”

Sprint pinged the phone 15 times until police confirmed that Caraballo’s car was at a local McDonald’s. That led to Caraballo’s arrest, at which point he made incriminating statements. Caraballo moved to suppress the statements as fruit of an unlawful search of his phone when police “pinged” it. The government responded that the pinging was not a search; if it was a search, it was a reasonable search based on exigent circumstances; and if it was an unreasonable search, the good-faith exception to the exclusionary rule applied.

The court’s opinion notes the uncertainty of whether a search occurred at all. The opinion bypasses this question by assuming that a search occurred and ruling only that any search was reasonable because it was justified by exigent circumstances. As some readers know, exigent circumstances are usually based on a pressing emergency. The basic idea is that if the government has to act quickly, because the evidence would be gone or the public harmed by the delay in getting a warrant, then the government can conduct a warrantless search or seizure as long as it is reasonable under the totality of the circumstances.

The court’s analysis of exigent circumstances breaks down into two parts. The first is what you might call traditional exigent circumstances analysis. Caraballo was a suspect in a violent killing who might have been armed, and if he killed the victim, he might try to kill others, including government informants who had turned against him. Also, the officers testified that although it would have taken only six hours to get a warrant, it probably would have taken “days or weeks” for Sprint to execute the warrant and ping the phone.

I think these arguments provide a pretty weak basis for exigent circumstances. The case that Caraballo was behind the killing was plausible but not strong, and the grounds for thinking he was going to hurt others if he was behind the killing itself seem pretty speculative. The concern that Sprint might delay in executing the warrant is interesting, although it’s not obvious that it provides an argument against getting a warrant in the first place (especially given that the officers believed they had probable cause that Caraballo was a drug dealer but not that he was the killer). But at least these arguments are sound in traditional exigent circumstances analysis, so they’re pretty fact-bound points.

The second part of the exigent circumstances analysis is more doctrinally novel. Judge Calabresi quotes a passage from a prior case saying that the amount of force and the degree of privacy invasion used in carrying out a search and seizure are relevant to reasonableness. From that, he deduces a somewhat different principle:

We read this language to mean that the greater the invasion of privacy, e.g., of a person’s home, see Florida v. Jardines, 133 S. Ct. 1409, 1414 (2013) (“[W]hen it comes to the Fourth Amendment, the home is first among equals.”), and the clearer the restrictions on police behavior in the absence of exigency, the more stringent the requirements that the search be urgently undertaken in order for the exigency exception to apply. In this respect, exigency analysis incorporates both principles of objectively proper officer behavior and the degree of privacy invasion involved.

The fact that the officers apparently acted in good faith and that their conduct may not have been a search at all then weighs in favor of exigent circumstances:

At the same time, and significantly, the degree of the officers’ intrusion into Caraballo’s privacy was relatively slight. First of all, the officers showed due regard for applicable law in conducting their search. In the words of the District Court, the officers “held a good faith, reasonable belief that there was a serious and imminent threat to human life and that federal law authorized a warrantless cell phone pinging in those circumstances.” Caraballo, 963 F. Supp. 2d at 346 (emphasis added). Indeed, not only was this belief consistent with the officers’ limited experience with pinging, but it was also endorsed by the county’s state attorney, who viewed the course of action as “appropriate.” Id.

Moreover, contrary to the privacy interests at stake in Dorman and MacDonald, any expectation of privacy that Caraballo had in his cell-phone location was dubious at best. Indeed, given that the search took place prior to the Supreme Court’s decision in United States v. Jones, 132 S. Ct. 945 (2012), Caraballo would have struggled to point to any authority that would support an argument that he had a reasonable expectation of privacy in this information. See United States v. Aguiar, 737 F.3d 251, 261 (2d Cir. 2013) (“The Supreme Court’s decision in [United States v. Knotts, 460 U.S. 276 (1983)] stood for the proposition that the warrantless use of a tracking device to monitor a vehicle on public roads did not violate the Fourth Amendment.”). Moreover, the fact that the question of the degree of privacy that adheres to these sorts of information, to date, divides those Circuit courts that have spoken to the issue reinforces the conclusion that the intrusion here was not to an established, core privacy value.

Pardon me for wading into the Fourth Amendment nerd zone, but I tend to think this analysis is mixing up doctrinal boxes. Fourth Amendment law has three basic questions: 1) what is covered at all (what is a search or seizure), 2) when is a search or seizure reasonable, and 3) what are the remedies for violations. The exigent circumstances doctrine is about the second question. But Judge Calabresi’s analysis seems to incorporate analysis from the first and third questions into the second.

Whether the government acted in good-faith belief of legality is generally a question of remedy, not whether the search was reasonable. Granted, the categories can blur (see Heien v. North Carolina), but it seems like more of a remedies question than a reasonableness question here. Similarly, whether a search occurred at all is a question to be analyzed under the first box rather than the second.

Perhaps the court’s approach reflects a wish to avoid a broad Fourth Amendment ruling. Exigent circumstances is a classic case-by-case doctrine, so the court could approve the government’s conduct here without saying much about other cases. There is a lot of value in a court proceeding cautiously in the face of new technologies and avoiding broad holdings. At the same time, there is also value in a court answering the hard questions raised when the three questions of Fourth Amendment law are kept distinct and a court has to answer them separately.