Cellphone Tracking in Texas

A look at real-time records and what they mean

By Pierre Grosdidier

In Sims v. State, The Texas Court of Criminal Appeals unanimously held that authorities did not violate a suspect's Fourth Amendment privacy rights when they "pinged" his cellphone less than five times over less than three hours without a warrant to locate and arrest him on suspicion of murder.1 The decision is consistent with Carpenter v. United States, where the U.S. Supreme Court held that a warrant was required to access seven days of cell-site location information, or CSLI.2 Carpenter was a narrow decision that left room for war-rantless requests for CSLI under exigent circumstances, such as when authorities “need to pursue a fleeing suspect, [or] protect individuals who are threatened with imminent harm.”3

Christian Sims’ grandmother was found dead from a gunshot at her home. Her car, purse, and two handguns were missing. Relatives immediately suspected her absent live-in grandson of the crime.4 Believing Sims to be armed and dangerous and acting without a warrant or even a court order, the police had the service provider proactively ping his cellphone to determine its location in “real-time.”5 The pings helped locate Sims, whom police arrested in possession of one of the guns, six knives, ammunition for a siege, and a bloodstained towel. At his trial for murder, Sims moved to suppress the real-time CSLI.6 He eventually pleaded guilty and received a 35-year sentence, reserving the right to appeal the trial court’s denial of his motion. The 6th Court of Appeals in Texarkana affirmed, and Sims petitioned the Texas Court of Criminal Appeals.

The court of appeals followed Carpenter’s reasoning. In that case, the U.S. Supreme Court had “recognize[d] that CSLI is an entirely different species of business record,” and it declined to extend the two lines of cases that have guided Fourth Amendment data privacy analysis.7 The linchpin of this analysis is that the Fourth Amendment protects a person’s subjective expectation of privacy “that society recognizes, or is prepared to recognize, as reasonable.”8

The first line of U.S. Supreme Court cases analyzed the legality of physical tracking devices. Under the public-thoroughfare rule, a “beeper” placed in a jug of chloroform that, along with visual surveillance of its ferrying vehicle, led authorities to a methamphetamine pro-duction site was held not to violate the Fourth Amendment. The court reasoned that the car’s travel on public roads was for all to see and the beeper conveyed only a limited amount of information.9 But, a GPS tracking device attached to a car for 28 days constituted a Fourth Amendment search, even if some of the travels occurred in public view.10 The second line of cases, which grew into the third-party doctrine, established that individuals have a reduced expectation of privacy in information that they knowingly share with others, such as bank records or phone numbers dialed from a home landline.11 The court held that the doctrine did not apply to CSLI because these records were not voluntarily surrendered to a service provider as were bank records or dialed numbers.12

Applying Carpenter, the Court of Criminal Appeals held that whether a CSLI data grab constituted a Fourth Amendment search turned on the amount of data seized. “There is no bright-line rule” and every situation “must be decided on a case-by-case basis.”13 But, in this case, fewer than five real-time pings in less than three hours were not enough to infringe on a person’s rea-sonable expectation of privacy.14

Importantly, the Court of Criminal Appeals declined to find a difference between historical CSLI records, as in Carpenter, and Sims’ real-time records, obtained by pinging his phone. A person’s expectation of privacy turned on the measure of the invasion, which in this case corresponded to the amount of data seized.15 Sims was apprehended in a few hours, but the police might want to track a suspect in real time “for days or even weeks.” Impliedly, a warrant would be required under these conditions, as with the GPS tracker in Jones. Both Carpenter and Simsraise the important question of how much historical CSLI triggers the need for a warrant. It might only take a few moments of well-timed historical CSLI from a small cell to confirm the presence of a person in a location to substantiate an alibi or a suspicion. Will courts require a warrant for such a circumscribed inquiry? TBJ


1. 569 S.W.3d 634, 46(Tex. Crim. App. Jan. 16, 2019).

2. Carpenter v. United States, 138 S. Ct. 2206, 2217 n.3 (2018).

3. Id. at 2220, 22-23 (“Our decision today is a narrow one.”).

4. Sims v. State, 526 S.W.3d 638, 640 (Tex. App.—Texarkana 2017) (affirmed).

5. Sims, 569 S.W.3d at 636-38 and n.1.

6. Neither the appellate nor the TCCA opinions dwell on this point, but we can surmise that by suppressing the CSLI, Sims tried to suppress the evidence collected at the time of his arrest.

7. Carpenter v. United States, 138 S. Ct. 2206, 2222 (2018).

8. Sims, 569 S.W.3d at 643 (citing Katz v. United States, 389 U.S. 347 (1967)).

9. Id. at 643-44 (citing United States v. Knotts, 460 U.S. 276 (1983)).

10. Id. at 644 (citing United States v. Jones, 565 U.S. 400 (2012)).

11. Id. (citing United States v. Miller, 425 U.S. 435 (2012)(bank records)); Smith v. Maryland, 442 U.S. 735 (1979) (phone numbers).

12. Id. at 645.

13. Id. at 646.

14. Id.

15. Id. at 645 n.15.

This article, which was originally published in Circuits, has been edited and reprinted with permission.

Headshot of Pierre GrosdidierPIERRE GROSDIDIER is an attorney in Houston. He belongs to the first group of attorneys certified in construction law by the Texas Board of Legal Specialization in 2017. His practice includes data privacy and unauthorized computer access issues and litigation. Prior to practicing law, Grosdidier worked in the process control industry. He holds a Ph.D. from Caltech and a J.D. from the University of Texas. Grosdidier is a member of the State Bar of Texas, an AAA Panelist, a registered P.E. in Texas (inactive), and the State Bar of Texas Computer & Technology Section secretary for 2019-2020.

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