By Kirk Goza, J.D. Candidate

This November the Supreme Court will hear oral arguments in a case that will have powerful implications for the future of privacy and police surveillance. That case, United States v. Jones(No. 10-1259), involves a challenge to a police practice that has split state and circuit courts for nearly a decade. The practice in question? Police use of GPS trackers to monitor suspects’ vehicles without a warrant. The Court’s decision will obviously impact the police’s use of GPS devices, but it could also shed light on a major ambiguity in Fourth Amendment law.

Florida v. Rileyand Competing Theories of “Reasonable Expectation of Privacy”

In 1989, the Supreme Court released a plurality opinion that highlighted two competing theories of Fourth Amendment law. That case, Florida v. Riley, involved police surveillance of a suspect’s marijuana-growing operation inside a greenhouse in the Florida everglades. Because the roof of the greenhouse was almost completely covered, Police were unable to view inside the greenhouse using a low-flying airplane. Instead, they hovered above the defendant’s property at an altitude of 400 feet, and were able to look through two missing roof slats to see marijuana plants growing inside. The question for the court was whether or not this police tactic violated the defendant’s “reasonable expectation of privacy.”

The plurality opinion, written by Justice White and joined by Justices Rehnquist, Scalia and Kennedy held that because members of the public had a legal right to fly a helicopter in that airspace, the police had not violated the defendant’s Fourth Amendment right to privacy.

Justices Brennan, Marshall, Stevens and Blackmun dissented, arguing that the standard should not be whether or not police had trespassed or otherwise violated the law, but whether or not the defendant could reasonably expect that members of the public would fly in that airspace and be able to view the inside of his greenhouse.

Justice O’Connor cast the deciding vote. She agreed with the dissent that the test should be whether or not members of the public would reasonably be expected to fly over the defendant’s greenhouse, but she nevertheless concurred with the plurality, concluding that the burden was on the defendant to present evidence that air traffic in the area was uncommon, which he failed to do.

It may seem self-evident that a helicopter hovering above houses is an unusual occurrence in the Florida Everglades, but let’s set that point aside. The competing opinions in Florida v. Riley highlight two competing schools of Fourth Amendment theory. Is activity “exposed to the public” simply because members of the publiccould have seen it, without breaking the law? Or must it be likely that members of the public would see it?

Over three decades have passed since Florida v. Riley was handed down, the Court’s membership has changed substantially, and no decision that I’m aware of has shed any light on those questions.[1] The Supreme Court’s decision this fall in United States v. Jones will be an important indication of what theory currently holds sway with the majority of the Roberts court.

A Brief Summary of 4th Amendment Law Pertaining to Jones

The Fourth Amendment protects the right of people to be secure against unreasonable searches. In Katz v. United States (1967), the Supreme Court defined the term “search” to include only activity that intrudes upon an individual’s “reasonable expectation of privacy.” Subsequent cases have held that a person has no reasonable expectation of privacy in activity that they “expose to the public.” Thus, when police monitor activity that is exposed to the public, they have not conducted a search, and therefore don’t need a warrant.

In 1983, the Court decided a case that is particularly relevant to the issue presented in Jones. In United States v. Knotts, law enforcement used a radio-tracking device to track a drum of chloroform as it was driven to a suspected methamphetamine-manufacturing site. The Court held that the device didn’t violate the defendant’s Fourth Amendment rights because his activity was “exposed to the public”; he had no “reasonable expectation of privacy” while driving a car on public roads.

United States v. Jones

The Court in United States v. Jones will have to decide whether or not the information obtained from a month of regular GPS tracking is protected by a “reasonable expectation of privacy.” The case is distinguishable fromKnotts on its facts.  In Knotts, police were only able to track the defendant’s movements during a three-hour car ride. The defendant in Jones had his driving habits monitored 24/7 for an entire month. But is the information obtained by police in Knotts of an entirely different character than the information obtained by GPS tracking? Or is it simply more of the same information?

The answer may turn on which theory of Fourth Amendment rights you subscribe to. If you take the approach of Justice White from Riley, then the prosecution has a strong case. It would not be illegal for members of the public to follow someone around for a month. If members of the public could legally have seen the activity, then it was “exposed to the public” and not protected.

If, on the other hand, you take Brennan’s approach, then the defense would have the upper hand. It would be unusual indeed for a member of the public to follow Jones around, recording his every move for a month. Or perhaps if you take O’Connor’s view, it might not be so unusual.