MILWAUKEE (WITI) -- A Milwaukee murder is caught on camera. Police track down the killer in a matter of hours. Was it good detective work? Or an invasion of privacy? What police did is now a subject of debate before the Wisconsin Supreme Court.
Where should the court draw the line between justice and privacy? If you have a cell phone, the answer affects you.
According to the wireless industry, there are currently more than 326-million active mobile phones in the United States -- that's more cell phones than people. Last year, Americans made 2.3 trillion minutes worth of cell phone calls and sent more than 2.2 trillion text messages. Those transmissions were sent over a network of more than 300,000 cell phone towers, which keep records on all of it.
Justin Webb, an information security specialist at Marquette University, says most people don't realize the implications of the smart phone they carry with them everyday.
"You're essentially carrying a tracker in your pocket," Webb says.
Even when you're not using your phone, it is constantly identifying itself to the nearest cell phone towers.
"You may not be checking in on Foursquare," Webb says, "but Verizon or AT&T, they know exactly where you are, all the time."
And more often than you might think, so do police.
But just how and when police can use the data collected by wireless providers is now a subject of debate before the Wisconsin Supreme Court. Last month, justices sat for the first time ever in the Sheboygan County Courthouse as part of the court's "Justice On Wheels" program, in which cases of interest to the general public are heard in locations outside of Madison. Attorney Casey Hoff delivered a summary of Wisconsin vs. Tate, for the benefit of the audience.
"This case, I think, has real implications for both privacy and law enforcement goals," Hoff said.
The case involves a Milwaukee homicide that took place on June 9th, 2009. It was a seemingly random shooting near 16th and Locust that was captured on the surveillance camera of a nearby corner store.
Milwaukee Police declined to release video of the fatal shooting to FOX 6 News, but the department did release other videos, including one which shows the suspect purchasing a cell phone inside the store just minutes before the shooting.
According to court records, the suspect walked outside the store, approached a yellow car on the street, shot a man in the back of the head, then ran off.
The shooting killed 24-year-old Jarvis Banks. Police never did determine a motivation for the killing, but it took them just six hours to find the man responsible -- Bobby Lee Tate.
"It was remarkable police work," says Jeffrey Kassel, an Assistant Attorney General arguing on behalf of the State of Wisconsin.
Tate was sentenced to 39 years in prison, but that conviction is now in question, because of the way police found him... by tracking the phone he bought just before the shooting.
"And that's really what's at issue here," Hoff explains, "is tracking somebody in real time, wherever they are."
All police had was a first name and a phone number. And that phone did not have GPS, so police relied on data from the three closest cell phone towers to estimate the phone's location, a technique called 'triangulation.'
Once police had narrowed the search to a general area, they mounted a special antenna on top of their squad car called a 'stingray.' It mimics a cell phone tower and can force a target phone to communication its location. The closer they got to the phone, the stronger the stingray's signal.
"Like playing 'hot and cold,'" Webb explains. "You walk towards where that person is."
It didn't take long for police to trace the phone to an apartment building at 57th and Hampton. But it's a large building that takes up an entire city block, so even that wasn't quite good enough.
Police could tell the phone was somewhere on the east end of the building, so they went inside and started knocking on doors, telling residents they were looking for a person who committed a terrible crime. Inside Apartment 110, they found Bobby Tate hiding in a back bedroom. But that's not all.
"They found a white striped shirt," Hoff says. "They also found shoes with blood on them. And Bobby Tate was arrested for homicide."
After his conviction, Tate appealed, arguing the search warrant police used to track his phone was invalid, because it did not specify what evidence they were trying to collect.
Most of the time, when police request cell phone records, they're looking for things like a log of recent phone calls or incriminating text messages. But in this case, Tate's lawyer argues they weren't looking for evidence at all -- they just wanted to find their suspect.
'The location was not evidence of a crime," said Byron Lichstein, the attorney arguing on behalf of Bobby Tate.
During oral arguments last month, some of the justices challenged that theory.
"Why isn't the cell phone evidence of a homicide?" asks Patience Roggensack, Supreme Court Justice.
"Someone purchased the cell phone wearing these clothes on video," recounts Justice Ann Walsh Bradley, "[walks] outside, shoots, same clothes, walks out with the cell phone on outside video. What am I missing?"
Chief Justice Shirley Abrahamson compared the feeling of the case to George Orwell's infamous "Big Brother."
"It smells of government is watching all the time," she said.
The government's own lawyer acknowledges this case could give police the green light to use mobile networks to search for any suspect in any case.
"I understand as a policy issue, the concern," Kassel says.
But for many cell phone users we spoke to, that's okay.
Howard Snyder: "I don't really have a big problem with it."
Rafael Johnson: "Anybody in their right mind would like police to have that information."
Jim Taugher: "If you're not doing anything wrong, you got nothing to worry about."
Now the state's highest court will decide where to draw the line between justice and privacy.
"It's good police work to catch people," Abrahamson said. "[but] the 4th amendment is not designed to protect the criminal. It's designed to protect the rest of us from government intrusion."
This is one of two cell phone tracking cases the Wisconsin Supreme Court is set to decide in the coming months. The other involves a Kenosha man who stabbed another man to death and was eventually caught using the GPS tracking signal from his smartphone.
In that case, too, the primary question is can police use cell phone location information to find criminal suspects. And, if so, do they need a search warrant?