During a routine oil change in 2010, Yasir Afifi "noticed something weird" stuck to the undercarriage of his car.
His mechanic yanked off a mysterious black box attached to the rear bumper.
Afifi, a 20-year-old college student living in California, went home and posted pictures of the box on a social networking site and learned it was a tracking device. And then he got a surprise visit from the FBI asking him to turn over the device, called a Global Position System (GPS).
According to Afifi, the FBI agents asked him whether he was affiliated with an extreme religious organization, or had travelled to Yemen, Iran or Syria.
"I told them no," Afifi said. He gave them the device, "and I never heard from them again."
Afifi thinks he might have been targeted because he'd travelled to Egypt and his late father was a religious figure in the community. He filed suit in federal court, arguing that the attachment of the device and the FBI's use of it violated his constitutional rights.
"I shouldn't be treated this way," he said. "I'm an American citizen."
Lower courts have split on the issue of whether the warrantless use of such a device on a car travelling on a public street violates the Constitution's ban on unreasonable search and seizure.
On Tuesday, the U.S. Supreme Court will delve into the issue and hear a similar case stemming from the use of a GPS device to track a drug suspect in Washington, D.C. Afifi's case has been stayed pending the resolution of the Supreme Court case.
The case in front of the court -- United States v. Jones -- deals with the conviction of Antoine Jones, who owned and managed a nightclub in Washington, D.C. Jones was convicted of drug charges after law enforcement used a variety of techniques to link him to co-conspirators.
One technique was an electronic tracking device, installed secretly without a valid warrant on a Jeep used by Jones.
An appeals court in Washington, D.C., reversed Jones' conviction, finding that the evidence obtained with the GPS device was in violation of the Fourth Amendment protection against unreasonable search and seizure.
Judge Douglas H. Ginsburg, writing for the majority of a three-judge panel of the United States Court of Appeals for the District of Columbia, differentiated between a conventional 24-hour surveillance conducted by law enforcement on public streets and the GPS technology that tracked Jones' movements on such streets 24 hours a day for nearly a month.
"Here, the police used the GPS device not to track Jones' movements from one place to another, but rather to track Jones' movements 24 hours a day for 28 days as he moved among scores of places, thereby discovering the totality and pattern of his movements from place to place."
The judge said that new technology tracking the totality of an individual's movement was different from traditional surveillance techniques.
"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," Ginsburg wrote. "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."
Lawyers for the Obama administration are appealing the decision, arguing in court papers that all the Jeep's movements were "unquestionably exposed to public view" and, therefore, Jones did not have a "justifiable expectation that his public movements would remain invisible to private or government observation."
But Walter Dellinger, a lawyer for Jones, argued, "You may understand that your neighbor can observe you on a public street. What you cannot expect is that a neighbor would attach a GPS to your car and disclose your every movement."
The justices will also discuss whether the attachment of the device to the car parked in a private driveway violated the Fourth Amendment.
Privacy rights advocates say the case illustrates how new technology has transformed the debate regarding the Fourth Amendment's protection against unreasonable search and seizure.
"We are talking about a warrant, more precisely whether you have a reasonable expectation of privacy in your movements in the public space over a period of time," said Marcia Hofmann of the Electronic Frontier Foundation.
"In past times, it was very difficult to capture a comprehensive understanding about a person's movements because of the transactional costs associated with that," Hoffman said. "But with technology being the way it is these days, it is very easy. If police didn't need a warrant, they could follow anybody anytime."
Catherine Crump, an attorney with the American Civil Liberties Union, said the challenge is only the first of many the court will have to face, including the use of cell phones to track movement.
"Law enforcement has many new technologies, including facial recognition software that allows it to identify one person out of a large crowd, and x-ray technology that makes it possible to see through clothing," she said.
"This court is going to have to decide whether to treat these technologies as if they are no different from the old ones, or whether it will recognize they pose a new threat to privacy and civil liberties."