Technology June 2023

Reasonable Expectation of Privacy

E-Scooter location tracking does not violate the Fourth Amendment.

Written by Pierre Grosdidier

Electric scooters, or E-Scooters, easily rentable via smartphone applications, increasingly pepper urban landscapes. In 2018, faced with cluttered sidewalks, the city of Los Angeles started to require e-scooter companies to track each of their wheeled devices in real-time via their smartphone applications by recording their whereabouts.1 Importantly, the data collection does not include rider-related information. Justin Sanchez, an e-scooter rider, sued the Los Angeles Department of Transportation, or LADOT, alleging, inter alia, that the location tracking violated the Fourth Amendment. Sanchez alleged that the LADOT could easily deanonymize the location data with the help of other data sets and retrace riders’ past whereabouts with preserved historical data. The district court dismissed Sanchez’s complaint without leave to amend and the U.S. Court of Appeals for the 9th Circuit affirmed, holding that the third-party doctrine applied and foreclosed his reasonable expectation of privacy in his location data.2

The court whittled down Sanchez’s claim to whether the collection of e-scooter location data violated Justice John Marshall Harlan II’s Katz test, under which a search requires a Fourth Amendment warrant when a person “exhibit[s] an actual (subjective) expectation of privacy . . . that society is prepared to recognize as ‘reasonable.’”3 The court addressed this issue by considering the tension between a person’s expectation of privacy in their whereabouts and the third-party doctrine, which holds that a person has no such expectation in information that the person voluntarily makes public. As to a person’s whereabouts, the U.S. Supreme Court narrowly held in Carpenter v. United States that collecting a person’s historical cell site location information, or CSLI, for 127 days required a warrant because it “achieve[d] near perfect surveillance” and violated the person’s reasonable expectation of privacy.4 But Carpenter did not disturb the third-party doctrine.5 In United States v. Miller, the Supreme Court held that Jack Miller had no expectation of privacy in canceled check and other transactional information held by his bank and sought by the government.6 Likewise, in Smith v. Maryland, the court held that Michael Lee Smith had no expectation of privacy in the phone numbers he dialed and that a police pen surreptitiously recorded.7 In both cases, Miller and Smith had voluntarily communicated the information to third parties (the bank and the phone company, respectively), thus diminishing their privacy interests. Importantly, in Carpenter, the Supreme Court held that CSLI is “not truly” voluntarily shared with the phone companies because phones generate CSLI automatically in the background, and because carrying a cellphone is “indispensable to participation in modern society.”8

In this case, the 9th Circuit held that the third-party doctrine applied because Sanchez knowingly and voluntarily disclosed his location data each time he rented an e-scooter. He agreed each time to the operator’s privacy policies, which stated explicitly that location data would be collected and shared with authorities. Moreover, in a significant departure from the facts in Carpenter, the location data concerned e-scooters, not their riders. A particular rider could not expect to use the same device multiple successive times as riders grabbed e-scooters willy-nilly on the street and operators rotated them for recharge. The location data, therefore, did not track any individual rider “virtually continuously” as did CSLI. Finally, in another departure from Carpenter, e-scooters are not indispensable to function in today’s society as cellphones are. E-scooters are merely one short-distance transportation solution among others. Concluding that the third-party doctrine applied, the court held that, in this case, the location data collection was not a Fourth Amendment search. The court stressed the narrowness of its decision, leaving the door open to other outcomes if the location data was used by law enforcement or to infer riders’ identities and whereabouts.9 TBJ

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


1. Sanchez v. Los Angeles Dep’t. of Transp., 39 F.4th 548, 552 and n.3 (9th Cir. 2022) (the three-judge panel included Rosenthal, C.J. S.D. Tex., sitting by designation).
2. Id. at 553, 559.
3. Katz v. United States, 389 U.S. 347, 361 (1967)(Harlan, J., concurring).
4. Sanchez, 39 F.4th at 556 (citing and quoting Carpenter
v. United States
, --- U.S. ---, 138 S. Ct. 2206, 2217–18 (2018)).
5. Id. (citing and quoting Carpenter, 138 S. Ct. at 2220 (“We do not disturb the application of Smith and Miller”)).
6. Id. at 557 (citing United States v. Miller, 425 U.S. 435, 438–39 (1976)).
7. Id. (citing Smith v. Maryland, 442 U.S. 735, 740 (1979)).
8. Id. at 559 (citing and quoting Carpenter, 138 S. Ct. at 2220).
9. Id. at 559-61.

Headshot Natalia ShehadehPierre Grosdidier is a litigation attorney in Houston. He is certified in construction law by the Texas Board of Legal Specialization. Grosdidier’s practice also includes data privacy and unauthorized computer access issues and litigation. Prior to practicing law, he worked in the process control industry. Grosdidier holds a Ph.D. from Caltech and a J.D. from the University of Texas. He is a member of the State Bar of Texas, an AAA Panelist, a registered P.E. in Texas (inactive), a member of the Texas Bar Foundation, a fellow of the American Bar Foundation, and the State Bar of Texas Computer & Technology Section chair for 2022-2023. He was elected medium section representative to the State Bar of Texas Board of Directors for the 2023-2026 term.

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