GPS Surveillance: A Crossroads for the Fourth Amendment

November 7, 2011
Guest Post

By Daniel J. Solove. Solove is the John Marshall Harlan Research Professor of Law and the George Washington University Law School. He is the author of Nothing to Hide: The False Tradeoff Between Privacy and Security (Yale 2011).


The Supreme Court has long held that there is no expectation of privacy in public for the purposes of the Fourth Amendment.  Because the Fourth Amendment turns on the existence of a reasonable expectation of privacy, the Court’s logic means that the Fourth Amendment provides no protection to surveillance in public.  In United States v. Jones, the Court will confront just how far this logic can extend.  FBI agents installed a GPS tracking device on Jones’ car and monitored where he drove for a month without a warrant.  Jones challenged the warrantless GPS surveillance as a violation of the Fourth Amendment.  The D.C. Circuit agreed with Jones.  United States v. Jones, 615 F.3d 544 (D.C. Cir. 2010).  Other federal circuit courts have reached conflicting conclusions on GPS, and now the Supreme Court will resolve the conflict. 

Will the Court revisit its view about the lack of privacy in public given the changing capabilities of technology?  Or will it follow its tortured logic to the end, and maintain its wooden and antiquated rule of no expectation of privacy in public? 

On its face, the D.C. Circuit opinion appears to clash with the Supreme Court’s decision in United States v. Knotts, 460 U.S. 276 (1983), where the police installed a much simpler tracking device (referred to as a “beeper”) to a person’s car.  The Court concluded that the Fourth Amendment did not apply to the beeper because a “person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements.”

The D.C. Circuit distinguished Knotts because the Supreme Court noted in Knotts that the beeper surveillance was limited and explicitly noted that more pervasive surveillance might be treated differently.   In concluding that the Fourth Amendment requires a warrant to engage in extensive GPS surveillance, the D.C. Circuit noted that “[w]hen it comes to privacy . . . the whole may be more revealing than the parts.”  As the court reasoned:

It is one thing for a passerby to observe or even to follow someone during a single journey as he goes to the market or returns home from work. It is another thing entirely for that stranger to pick up the scent again the next day and the day after that, week in and week out, dogging his prey until he has identified all the places, people, amusements, and chores that make up that person's hitherto private routine.

The Supreme Court will determine if it agrees with this theory. 

The problem with the Court’s existing view of no privacy in public is that people often do expect privacy in public.  The Court’s conception of privacy wrongly views privacy as total secrecy and fails to recognize that people often have practical obscurity in public.  

Let’s look past conceptions of privacy and ask a more simple question: Should the government be required to obtain a warrant (prior judicial authorization) before installing a GPS device on a person’s car?   The answer seems clear – yes.  GPS surveillance is quite pervasive and far-reaching; it is an enormous exercise of government power, and one that is best regulated with judicial oversight rather than left to the unfettered discretion of law enforcement officials. 

Instead of asking this simple question, the Court must wade through its morass of cases about whether there’s a reasonable expectation of privacy.  These cases, which are at least purportedly attempting to gauge societal expectations of privacy, have never involved looking to empirical evidence or other social science.  Instead, the Court just declares by fiat whether there is or isn’t a societal expectation of privacy.  These declarations have no connection to what society actually expects.  The Court is really applying a this-is-what-we-think-should-be-private test.

Much will turn on whether surveillance occurs in public or private, but the harms of surveillance occur regardless of where surveillance occurs.  Surveillance in public can still chill behavior; it can limit people’s freedom; and it can give an enormous amount of power to the watchers. 

Applying the Fourth Amendment to GPS surveillance won’t mean stopping the government from engaging in it.  It will just mean that law enforcement officials who engage in GPS surveillance will be subjected to judicial oversight and will be required to justify their need to engage in the surveillance before doing so.  These requirements seem reasonable given the fact that GPS surveillance technology can track a person so pervasively.

I think the Court needs to draw a line, or else technology will make the Fourth Amendment virtually irrelevant.  I propose the following line be drawn:  The Fourth Amendment applies to a surveillance technology used in public if the surveillance technology: (1)  extends significantly beyond human capabilities; and (2) is used in a manner beyond its ordinary use by the general public.

In the cases where the Court held that there was no reasonable privacy in public, one underlying rationale is that law enforcement officials should be able to observe things just like anyone else.  So if a police officer sees a criminal walking down the street with a bag of cocaine, the police officer shouldn’t be required to cover her eyes.  Some degree of technological enhancement of the officer’s senses is also fine.  But this is a far cry from technological enhancement that fundamentally alters what human beings can do in such an extensive manner.  It’s one thing to use glasses to enhance vision; it’s quite another to use X-ray goggles to see through things. 

“But GPS technology is just a more systematized way for police to monitor movement in public,” some might say.  “The police could theoretically follow a person’s car around 24/7 for a long period of time.” 

Saying this, though, is like saying that a person could theoretically remember everything stored in a 200 Gigabyte hard drive.  Fourth Amendment protection shouldn’t turn on theoretical possibilities that are totally impractical.  It should turn on when it is most necessary and sensible to require judicial oversight of law enforcement activities.