Last year, the United States Marshal’s Service tracked down a fugitive named Steven Denson to a house in Witchita, Kansas. Before they stormed the house, however, they took a sensible precaution and placed a radar device on the outside of the wall to determine the location of the individual in the house. They then entered the house, arrested the fugitive, and found a number of illegal guns as well.
The marshals had a warrant for Denson’s arrest, but they did not have a search warrant for the home. Thus, they were only permitted to enter the home if they had “reason to believe” that Denson was inside the home at the time. Denson challenged the entry into the home, arguing that the police officers only developed a reason to believe he was inside after using the radar device, which violated his Fourth Amendment rights.
The Tenth Circuit rejected Denson’s argument and held that the officers did not violate the Fourth Amendment. According to the court, the officers already had reason to believe that Denson was inside even before they used the radar device. Thus, the court applied the independent source doctrine from the Supreme Court’s holding in Murray v. United States and allowed the search to stand without resolving the question of whether the radar device violated Denson’s Fourth Amendment rights. Here is the Tenth Circuit’s description of the device:
the government brought with it a Doppler radar device capable of detecting from outside the home the presence of “human breathing and movement within.” All this packed into a hand-held unit “about 10 inches by 4 inches wide, 10 inches long.” The government admits that it used the radar before entering — and that the device registered someone’s presence inside. It’s obvious to us and everyone else in this case that the government’s warrantless use of such a powerful tool to search inside homes poses grave Fourth Amendment questions. New technologies bring with them not only new opportunities for law enforcement to catch criminals but also new risks for abuse and new ways to invade constitutional rights. See, e.g., Kyllo v. United States, 533 U.S. 27, 33-35 (2001) (holding that using warrantless thermal imaging to show activity inside a home violated the Fourth Amendment). Unlawful searches can give rise not only to civil claims but may require the suppression of evidence in criminal proceedings. We have little doubt that the radar device deployed here will soon generate many questions for this court and others along both of these axes. At the same time, in a criminal proceeding like ours the government is free to rely on facts gleaned independently from any Fourth Amendment violation.
This analysis seems cautious to a fault. There is no conceivable way that the use of the radar device is consistent with the Kyllo case. If law enforcement officers are conducting a Fourth Amendment search when they use a thermal imager to detect the emanations of heat inside of a home, then they are certainly conducting a Fourth Amendment search when they use a radar to detect the presence, movement, and location of individuals inside a house. And although these devices are apparently becoming more and more popular among law enforcement, they have certainly not risen to the level of being “in general public use,” as required by Kyllo.
The use of the radar device to establish probable cause is even more clearly unconstitutional given the Supreme Court’s recent case of Florida v. Jardines, which held that a drug-dog sniff at the front door of a house constituted a Fourth Amendment search. In Jardines, the court held that the use of a surveillance tactic which ordinarily does not implicate the Fourth Amendment becomes an unconstitutional search when it is used at the front door of a home. In the Tenth Circuit’s case, the court was reviewing a surveillance tactic that is more intrusive than the thermal imager in Kyllo and which involved a United States Marshall placing the device directly on the outer wall of a home–a location where an individual arguably has a greater expectation of privacy than the front door.
Regardless, the Tenth Circuit’s holding in this case was almost certainly correct. Even without the information from the radar device, the United States Marshals had sufficient evidence to establish probable cause (or at least “reason to believe,” which may be an even lower standard) that Denson was in the home. Denson was the primary account holder on the utility for the home; and he was unemployed and running from the police, and the electric meter was “going faster than normal”–all of which would lead the officers to believe that someone was home at the time. Furthermore, the use of the radar device by the marshals seems perfectly legitimate in this case–once the marshals had established probable cause to believe that Denson was inside, they used the device to ensure their safety for when they entered the house. This is a perfectly reasonable, non-investigatory use of the technology.
But even though the marshals acted properly and the Tenth Circuit reached the proper result, one could still hope that the court had been a little bolder with its dicta regarding the radar device. Surely the question of whether the use of the radar gun was consistent with Kyllo had been fully briefed and argued by both sides, and thus there was no reason not to firmly state that the use of this device to establish probable cause violates the Fourth Amendment. Instead, the court decided to avoid the issue and save it for another day. This inevitably means that in some future case, a law enforcement officer will use a radar device to establish probable cause in the fruitless hope that this kind of surveillance is constitutional–with the result that the defendant’s conviction will be overturned and a criminal will walk free. Stronger guidance on this point might have avoided that unfortunate result.