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United States v. Morgan

United States District Court, District of Columbia

March 5, 2018




         Before the Court is defendant's motion in limine to exclude the government's proposed cellular analysis testimony.[1] For the reasons explained below, the Court denies defendants' motion with the qualification that Special Agent Kevin Horan may not testify or imply that he can pinpoint a person's exact location using drive testing.


         On March 23, 2017, the government filed an expert disclosure letter indicating that it intended to call FBI Special Agent Kevin Horan as an expert in the analysis of cellular telephone records. (ECF No. 39.) The type of cellphone-data analysis used in this case involves a method called drive testing. The government seeks to admit the expert testimony of Special Agent Kevin Horan of the FBI's Cellular Analysis Survey Team (“CAST”) concerning (1) counts dealing with defendant's alleged kidnapping, transportation of a minor with intent to engage in criminal sexual activity, and attempted production of child pornography and (2) counts dealing with defendant's failure to register as a sex offender. (Government's Opp. to Def.'s Mot. in Limine, ECF No. 48, (“Gov. Opp.”) at 1-2.) As to the substantive counts, Agent Horan's testimony will analyze the cell-site information and data obtained from defendant's cellphone and the alleged victim's cellphone as it relates to the time frame of the offenses alleged to have occurred on May 22-23, 2016. (Id. at 2.) As to the registration counts, Agent Horan's testimony will analyze the cell-site information and data obtained from defendant's cellphone records during a time period between 2015 and 2016. (Id.)

         On April 3, 2017, defendant moved to exclude the government's proposed cellular analysis testimony on the grounds that Agent Horan's opinions (1) depend on unreliable methodologies, Fed.R.Evid. 702, and (2) otherwise pose a danger of unfair prejudice that substantially outweighs the proposed testimony's probative value, Fed.R.Evid. 403. (Def.'s Mot. in Limine, ECF No.44, (“Def.'s Mot.”) at 1.) After initial briefing and a Daubert hearing that took place over three days, the Court allowed the parties to submit post-hearing briefing. Defendant filed his post-hearing brief on January 13, 2018, and the government filed their response on February 26, 2018. The Court is now in a position to rule on defendant's motion in limine.



         Federal Rule of Evidence 702 governs the admissibility of expert testimony in federal courts and provides that a witness may offer expert opinion testimony if:

(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based upon sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case.

Fed. R. Evid. 702. The Supreme Court has explained that trial judges must “ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable.” Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579, 589 (1993); see also Kumho Tire Co. v. Carmichael, 526 U.S. 137, 147, 150 (1999).

         An opinion exhibits reliability if the expert is qualified to offer the opinion and the opinion has an acceptable basis in the knowledge and experience of the expert's discipline. See Daubert, 509 U.S. at 592-93, 597; United States v. Williams, 827 F.3d 1134, 1156 (D.C. Cir. 2016), cert. denied sub nom. Edwards v. United States, 137 S.Ct. 706 (2017). The Supreme Court has detailed several non-exhaustive factors to assess a theory or technique's reliability- (1) whether the theory or technique at issue can be tested or has been tested, (2) whether the theory or technique has been subject to peer review and publication, (3) whether the theory or technique has a known or potential error rate, and (4) whether the relevant expert community generally accepts the theory or technique. See Daubert, 509 U.S. at 594; Kumho Tire Co., 526 U.S. at 150. Still, the Rule 702 inquiry is a “flexible one, ” and this list is not exhaustive or determinative. See Daubert, 509 U.S. at 594; see also Kumho Tire Co., 526 U.S. at 150.

         A relevant opinion will help the trier of fact understand evidence or determine disputed facts. See Daubert, 509 U.S. at 592-93, 597; Williams, 827 F.3d at 1156. “If a court determines that expert testimony might be helpful to the jury, it should allow the testimony unless it finds that under Rule 403 the unfair prejudice caused by the testimony outweighs its probative value.” United States v. Gatling, 96 F.3d 1511, 1523 (D.C. Cir. 1996); see also Daubert, 509 U.S. at 595.


         At the first day of the Daubert hearing, the Court qualified Agent Horan as an expert in historical cell-site analysis and drive test analysis without objection from defendant. (Tr. of Daubert Hr'g (Day 1), Aug. 22, 2017, ECF No. 74 (“8/22/2017 Tr.”) at 10-11.) However, it is necessary to briefly review Agent Horan's qualifications given the lack of independent scientific analysis on the use of cell-site data for law enforcement purposes.

         Kevin Horan is a FBI special agent who has been a member of the FBI's CAST unit since its inception in 2007. (Id. at 4.) Agent Horan was using cellphone records in criminal investigations prior to joining CAST, but when CAST was formed in 2007, there were few, if any, subject matter experts in the field of cellular analysis for criminal investigations. (See Id. at 4.)

         Agent Horan underwent specialized training upon joining CAST, which includes: (1) education on radiofrequency theory and analysis; (2) instruction from major cell service providers and their radiofrequency engineers on network maintenance and operation; (3) education and applied training on the use of drive test gear and scanning gear; and (4) a concluding series of practical exercises on use of historical cell records. (Id. at 5-7.) Initial CAST training ends with a drive test evaluation, moot court session, and final exam. (Id. at 7.) In addition, CAST members have a yearly retraining course that includes instruction on any relevant updates and a recertification in an agent's current drive test equipment or a certification in new drive test equipment. (Id.; Tr. of Daubert Hr'g (Day 2), August 29, 2017, ECF No. 73 (“8/29/2017 Tr.”) at 34-35.)

         Agent Horan performs between 20-30 drive tests a year, and also teaches classes on drive testing and historical cell records analysis. (8/22/2017 Tr. at 9.) He has a valid certification to use his current drive test equipment. (Id. at 22.) Agent Horan has been certified as an expert in court on cellphone analysis at least 76 times, and “in the last several years, almost every one of [his] cases involved [a] drive test.” (Id. at 10.)


         At issue here is the reliability of drive testing, which “is a method used by wireless telephone companies and radio frequency engineers to determine the coverage range of a cell tower for the purpose of determining the health of the telephone company's wireless network.” Larry Daniel, Cell Phone Location Evidence for Legal Professionals: Understanding Cell Phone Location Evidence from the Warrant to the Courtroom 69 (2017). Providers did not design drive testing methods for establishing a permanent footprint of a tower's coverage area, nor did they design drive testing to establish a cellphone's exact location when it communicates with a tower. Id. In its current form, drive testing cannot determine the exact “location of a cell phone or set[] exact boundaries for where a cell phone must be to connect to a particular cell tower.” Id. at 70. As with all tests involving human inputs, “drive testing results can be skewed by the method used by the person doing the testing. It can also be skewed by whether or not the person doing the testing has the drive testing equipment calibrated by a qualified calibration engineer. Generally, calibration happens once a year.” Id.

         Drive testing cannot perfectly replicate how a cellphone would interact with a network on a past date. See Id. at 77. Drive testing “is a test to determine if at the time of the drive test and in the location of the drive testing equipment, a phone can make an outgoing call and the phone can ‘hear' a signal from a cell tower.” Id. at 71. As evidence, results from a drive test can show

that a cell phone could be at a particular place and would prefer the cell site and sector that was recorded in the historical call detail records. Or the drive test results are used to create a map showing the limits of where a cell phone could be and connect to a cell tower or sector.

Id. at 76; (see also 8/22/2017 Tr. at 11-12 (describing how cellphones communicate with towers).) In other words, drive test results cannot “provide an exact location.” (8/22/2017 Tr. at 14; see also Id. at 61-62.)

         As a point of comparison, generating data from drive testing operates on many of the same principles as historical cell-site analysis. Compare Daniel, supra, at 29-40, 49-68, with Id. at 69-78. “Historical cell-site analysis can show with sufficient reliability that a phone was in a general area, especially in a well-populated one. It shows the cell sites with which the person's cell phone connected, and the science is well ...

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