November 20, 2019 Feature

The Intersection of the Fourth Amendment and Level 5 Vehicle Autonomy

By Ronald J. Hedges and Gail L. Gottehrer

Fast forward 10 years or so, when the vision of Level 5 autonomous vehicles (AV) on public roads will have become a reality. At Level 5, the AV will be fully autonomous: In other words, its performance should be equal to that of a human driver in every driving scenario. This means that humans will simply be passengers, rather than vehicle operators.

Now, let’s assume that a particular vehicle becomes the instrumentality of a crime or constitutes (or contains) evidence of a crime. Perhaps a passenger committed a murder and is using the AV to flee the crime scene. Or maybe a passenger, vehicle owner, or ride-hailing service user is delivering illegal drugs via the AV. What constitutional principles might come into play when law enforcement wants to stop the vehicle, arrest the passenger, and/or search for evidence? This thought exercise calls to mind Justice Samuel Alito’s concurring opinion in Brown v. Entertainment Merchants Association, 564 U.S. 786 (2011):

In considering the application of unchanging constitutional principles to new and rapidly evolving technology, this Court should proceed with caution. We should make every effort to understand the new technology. We should take into account the possibility that developing technology may have important societal implications that will become apparent only with time. We should not jump to the conclusion that new technology is fundamentally the same as some older thing with which we are familiar.

564 U.S. at 806.

Reviewing and Applying Existing Law

A logical place to start our analysis is with the so-called “automobile exception” to the Warrant Requirement of the Fourth and Fourteenth Amendments. After all, if our hypothetical Level 5 AV falls within that exception, we need go no further. The question is: Does it fall with this exception?

In Pennsylvania v. Labron, 518 U.S. 938 (1996), the Supreme Court set forth two justifications for the automobile exception, the first based on “ready mobility,” and the second on an individual’s reduced expectation of privacy given the “pervasive regulation” of automobiles. 518 U.S. at 940.

The Court confirmed that, once probable cause was established, a warrantless search of an automobile was permissible. But should the automobile exception apply to a Level 5 AV?

At first blush, the answer is likely no. The Level 5 AV will be subject to regulation at both the federal and state levels. Moreover, “ready mobility” will be a central feature of the Level 5 AV, especially if, as some have suggested, it will become a simple commodity to be rented, and fleets of Level 5 AVs will be common modes of transportation, much like taxis.

But our analysis does not end here. We need to look beyond the ability of law enforcement to conduct a warrantless lawful search of the Level 5 AV, and to address a separate question: Does the search of the vehicle infringe on the passenger’s Fourth Amendment rights? The Supreme Court addressed this in Byrd v. United States, 138 S. Ct. 1518 (2018). At issue in Byrd was whether the driver of a rented automobile, who was not listed on the rental agreement, had standing to challenge a warrantless search. The Court held that, “as a general rule, someone in otherwise lawful possession and control of a rental car has a reasonable expectation of privacy in it even if the rental agreement does not list him or her as an authorized driver.” 138 S. Ct. at 1524. It then remanded the case to the lower court to address “the Government’s argument that this general rule is inapplicable because, in the circumstances here, Byrd had no greater expectation of privacy than a car thief. If that is so, our cases make clear he would lack a legitimate expectation of privacy.” Id. The Court also remanded the case for a determination of whether, even if the petitioner had a right to object to the search, probable cause justified the search.

Now, back to our hypothetical. Assume the AV is stopped by law enforcement, presumably through an override feature built into the AV’s software. Is this a “seizure” for purposes of the Constitution? The Eleventh Circuit recently stated that, “[a] person suffers a ‘seizure’ of his property within the meaning of the Fourth Amendment when there is a ‘meaningful interference’ with his possessory interest in it.” United States v. Babcock, No. 17-13678, 2019 U.S. App. LEXIS 15506, at *7 (11th Cir. May 24, 2019) (Babcock).

The court went on to explain that

[w]hile the seizure of private property generally requires a warrant, the Supreme Court has interpreted the Fourth Amendment to allow a warrantless seizure when police can show both (1) probable cause to believe that property contains contraband or evidence of a crime and (2) an applicable warrant exception, such as exigent circumstances.

Babcock, at *7.

Absent these, “police may ‘briefly detain’ property—Terry-stop style—on the strength of reasonable suspicion alone.” Id. Let’s assume that our AV is owned by a rental car company that consented to the installation of the technology that enabled law enforcement to stop the vehicle. That consent presumably did not extend to the property of any passenger inside the AV (unless, of course, the rental agreement required the passenger to consent to a search of any personal property she placed in the AV).

In this scenario, not only has the passenger’s property been seized, but the passenger herself has likely been seized. As the Supreme Court recognized in Bredlin v. California, 551 U.S. 249 (2007),

[A] person is seized by the police and thus entitled to challenge the government’s action under the Fourth Amendment when the officer, by means of physical force or show of authority, terminates or restrains his freedom of movement . . . .

551 U.S. at 254 (internal citations omitted).

So, we have three separate potential seizures and searches when the Level 5 AV has been stopped: that of (1) the AV itself, (2) the passenger who may have committed a crime, and (3) the passenger’s personal property. Should the automobile exception apply to each of these?

Assuming the existence of probable cause, the exception should apply in the first situation. As to the second and third situations, absent showings of either probable cause or reasonable suspicion to justify a Terry-stop, a warrant will presumably be required.

The Road Ahead

Is this conclusion correct? Or, to heed Justice Alito’s caution, must we delve deeper into AV technology to determine whether that technology “fits” into existing precedent?

One question that might be asked arises out of the fully autonomous nature of the Level 5 AV. Does that nature—which removes the individual from the operation of the AV—call for a new look at the automobile exception? Given the nature of the AV, might courts look to Riley v. California, 573 U.S. 373 (2014), and determine that, given that the AV is more analogous to a cell phone rather than to a traditional automobile, such an analysis renders the automobile exception inapplicable to Level 5 AVs?

The intent of this thought piece is to encourage consideration of how existing Fourth Amendment case law might be interpreted in light of an emerging technology. Such consideration should be ongoing as new technologies arise and become features of everyday life—and of criminal behavior.


By Ronald J. Hedges and Gail L. Gottehrer

Ronald J. Hedges is a senior counsel with Dentons US LLP. He served as a United States Magistrate Judge in the District of New Jersey from 1986 to 2017. Hedges is a frequent writer and speaker on various topics related to electronic information and is the principal author of Managing Discovery of Electronic Information: A Pocket Guide for Judges, Third Edition (Federal Judicial Center: 2017). He may be reached at Gail Gottehrer is the founder of the Law Office of Gail Gottehrer LLC in Stamford, Connecticut, where her practice focuses on emerging technologies, including autonomous vehicles, AI, biometrics, and robotics, and the privacy, security, and other legal issues associated with the data collected and used by these technologies. She is chair-elect of the TIPS Automobile Litigation Committee and may be reached at