United States v. Pembrook
119 F. Supp. 3d 577
E.D. Mich.2015Background
- April 22, 2014: attempted robbery in Grand Rapids and a later (same day) successful Rolex robbery in West Bloomfield; four defendants charged including Calhoun and Johnson.
- FBI obtained cell-site location information (CSLI) from providers via four §2703(d) orders (Apr. 28, May 22, Aug. 5, Sept. 17, 2014) rather than search warrants; orders covered tower "dumps" around the stores and historical CSLI for several phone numbers over multi-week periods.
- Government’s analysis linked a phone allegedly used by Johnson to towers near both robberies and showed travel patterns tying several phones (including numbers attributed to Calhoun, Briley, Pembrook) from Philadelphia through Wisconsin/Michigan and back.
- Defendants (primarily Calhoun) moved to suppress the CSLI as a Fourth Amendment search and to exclude/limit the Government’s CSLI expert (SA Christopher Hess) under Daubert/Rule 702; Defendants also argued the SCA §2703 did not authorize tower-dump requests.
- District court held suppression denied (good-faith / reasonable-reliance and unsettled law at time of requests) and granted in part the Daubert motion: Hess admissible but Government ordered to supplement Rule 16 disclosure identifying sources for Hess’s “Basic Principles” used in his analysis.
Issues
| Issue | Plaintiff's Argument | Defendant's Argument | Held |
|---|---|---|---|
| Whether April 28 tower-dump and subsequent CSLI obtained under §2703(d) must be suppressed under the SCA because §2703(c) authorizes disclosures only “pertaining to a subscriber” | Calhoun: statutory text (singular) forbids broad tower-dumps; relief should be suppression | Government: even if SCA violation occurred, SCA does not authorize suppression as a remedy | Denied: suppression not available under SCA; statutory remedies limited and exclusion not a statutory remedy |
| Whether obtaining historical CSLI via §2703(d) orders (without a warrant) was a Fourth Amendment search requiring suppression | Calhoun: long-term CSLI reveals detailed movements / presence in private places (invoking Jones, Karo, Maynard) and tower-dump is a dragnet; warrants required | Government: at time of orders, binding and persuasive authority were mixed; voluntary-disclosure (Smith/Miller) and Knotts analogies made good-faith, objectively reasonable reliance on §2703(d) orders | Denied: suppression inappropriate because law was unsettled and government acted in objectively reasonable good faith; deterrence rationale for exclusion not satisfied |
| Whether expert Hess’s CSLI methodology (including any "granulization") is admissible under Fed. R. Evid. 702/Daubert | Calhoun: Hess’s methods insufficiently disclosed; relies on untested "granulization" and makes unsupported technical assumptions | Government: Hess will offer general, non-precise geolocation opinion; methodology (mapping CSLI to general geographic areas) accepted in many courts; details available | Granted in part: Hess may testify (Daubert gate passed) but Government must supplement Rule 16 disclosure to identify sources for Hess’s asserted “Basic Principles” |
| Whether additional discovery is required to permit effective cross-examination of the CSLI expert | Calhoun: needs sources/data supporting Hess’s principles and assumptions | Government: initial disclosure adequate but willing to supplement | Granted in part: court orders supplementation identifying sources; otherwise exclusion denied without prejudice |
Key Cases Cited
- Katz v. United States, 389 U.S. 347 (1967) (established reasonable-expectation-of-privacy test)
- United States v. Miller, 425 U.S. 435 (1976) (voluntary disclosure to third party defeats Fourth Amendment expectation)
- Smith v. Maryland, 442 U.S. 735 (1979) (third-party disclosure/pen register reasoning)
- United States v. Knotts, 460 U.S. 276 (1983) (no expectation of privacy in movements on public roads)
- United States v. Karo, 468 U.S. 705 (1984) (use of tracking technology revealing presence inside home implicates Fourth Amendment)
- United States v. Jones, 565 U.S. 400 (2012) (installation/use of GPS tracker is a search; concurrences discuss long-term monitoring privacy concerns)
- Davis v. United States, 564 U.S. 229 (2011) (exclusionary rule’s deterrence inquiry; good-faith reliance limits suppression)
- United States v. Warshak, 631 F.3d 266 (6th Cir. 2010) (reasonable expectation of privacy in e-mail contents—distinguished here because case involved content)
- United States v. Forest, 355 F.3d 942 (6th Cir. 2004) (cell-site data used as proxy for public movements; Knotts controlling)
- United States v. Skinner, 690 F.3d 772 (6th Cir. 2012) (cell-site tracking on public roads did not require warrant; comprehensive long-term tracking may raise concerns)