Regular readers will recall the    mosaic theory of the Fourth Amendment introduced by the DC    Circuit in     United States v. Maynard, by which law enforcement    steps that arent searches in isolation can become searches    when aggregated over time. For the most part, judges have been    pretty skeptical of the mosaic theory. For example, in the    recent oral argument in the Fourth Circuit in     United States v. Graham, on whether the Fourth    Amendment protects historical cell-site data, the mosaic    arguments didnt gain a lot of traction for the defense.  
    In this post, however, I want to focus on two recent federal    district court decisions that cut against this trend and    adopted the mosaic theory. The first case is United    States v. White (E.D.Mich. Nov. 24, 2014) (Lawson,    J.), which held that the Fourth Amendment was violated when    the government obtained a warrant to track a drug dealers cell    phone continuously over 30 days. The second case is United    States v. Vargas (W.D.Wash. Dec. 15, 2014) (Shea, J.),    which suppressed video evidence from a camera set up on a    public utility pole 100 yards away from the targets rural    house that showed what was happening on the targets front lawn    continuously for six weeks.  
    1. United States v. White  
    In United States v. White, agents were conducting a    wide-scale investigation into a known narcotics trafficker,    Jimmie White. Agents obtained two search warrants to track    Whites cell phone in real time for 30 days each, with the goal    of understanding the scope of Whites activities and to show    his involvement in narcotics crimes. When charges were brought,    White moved to suppress the location information obtained from    the cell phone location warrants. The case was heard before    Judge David Lawson (who, allow me to add, I have had the    pleasure of working with on the     Criminal Rules Committee). Judge Lawson recognized that the    Sixth Circuit had held in United    States v. Skinner that monitoring a suspects cell    phone location in real-time was not a Fourth Amendment search.    But Judge Lawson held that the facts of Whites case were    distinguishable:  
      [T]he surveillance in this case took place over an extended      time period  continuously for 30 days on two (or three)      separate occasions  and followed White into both public and      private spaces. Justice Alitos concurring opinion in Jones,      which drew support from a fifth justice, see Jones,      132 S. Ct. at 954-57 (Sotomayor, J., concurring), suggested      that the use of longer term GPS monitoring in investigations      of most offenses impinges on expectations of privacy.      Id. at 964 (Alito, J., concurring). The 4-week      tracking in that case was well over the line of      reasonableness, in his view. Ibid. (We need not identify      with precision the point at which the tracking of this      vehicle became a search, for the line was surely crossed      before the 4-week mark.). And the Skinner majority      acknowledged Justice Alitos concerns, allowing that [t]here      may be situations where police, using otherwise legal      methods, so comprehensively track a persons activities that      the very comprehensiveness of the tracking is unreasonable      for Fourth Amendment purposes. Skinner, 690 F.3d at      780. Skinner does not control the present case,      because the length and breadth of the tracking here extends      well beyond what any reasonable person might anticipate.    
    Judge Lawson then offered three reasons why 30 days of    monitoring Whites cell phone location violated his reasonable    expectation of privacy. First, it included Whites location    when he was at home. Second, Congress has enacted statutory    privacy protections for cell-site location. And third, 30 days    of monitoring allows the government to obtain a detailed    picture of a persons life. As a result, it is safe to say    that society would recognize that an interest in keeping these    movements private is reasonable.  
    Judge Lawson recognized that his approach raised a difficult    question of line-drawing: How long is long enough for    monitoring to constitute a search? He answers:  
      [C]ourts have confronted similar problems in the past. For      instance, how long may law enforcement detain property      waiting for a drug detection dog to arrive for a sniff before      the intrusion matures into a seizure? To find an answer,      courts must balance the nature and quality of the intrusion      on the individuals Fourth Amendment interests against the      importance of the governmental interests alleged to justify      the intrusion. United States v. Place, 462 U.S.      696, 703 (1983).    
      Under that rationale, it may be appropriate to track an      individual for a short time on public streets based on a      level of suspicion that is less than probable cause. See      Terry v. Ohio, 392 U.S. 1, 22 (1968) . . . Longer      surveillances may require more justification, and a case      might be made that the governments reasons underlying the      need for tracking  in the case of domestic terrorism, for      example  may call for less. The present case involves a      garden-variety drug trafficking crime, nothing more. The      blanket surveillance of an individual for thirty days at a      time cannot equate to a brief detention, however. The nature      and quality of an intrusion of that magnitude (in excess of      the the 4-week mark) tips the balance in favor of the      individual; it constitutes a breach of ones reasonable      expectation of privacy that requires the state to demonstrate      probable cause as a justification for the intrusion.      Jones, 132 S. Ct. at 964 (Alito, J., concurring).    
    This passage is interesting because it relies on caselaw    concerning reasonableness, not what is a search. If I    understand Judge Lawson correctly, he would say that even    short-term monitoring on public streets is a search, but one    that may be allowed based on only the Terry standard,    at least depending on the crime under investigation. Here Judge    Lawson goes significantly beyond Justice Alitos Jones    concurrence, which had adhered to Knotts and indicated    that short-term location monitoring is not a search at all.  
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Volokh Conspiracy: Two district courts adopt the mosaic theory of the Fourth Amendment