Since 2008, the ACLU of Michigan has been petitioning the Michigan State Police to turn over information about their use of so-called "data extraction devices" (or DEDs). Manufactured by Cellebrite, a mobile forensics and data services company headquartered in Israel, the devices can connect to cellphones and, even bypassing passwords, retrieve phone numbers, text messages, call history, photos and video.
The issue came to a head this week, after the ACLU published a letter it sent to the state police, demanding transparency and saying misuse of the device could be a Fourth Amendment violation. Michigan State Police issued a statement Wednesday, claiming that "it only uses the DEDs if a search warrant is obtained or if the person possessing the mobile device gives consent."
But civil liberties advocates say that law enforcement's response is insufficient.
ACLU: We Have 'Credible Information' That Device Was Misused
"They don't say anything about their past behavior. It's a carefully crafted statement," said Kary Moss, executive director of the ACLU of Michigan.
On a "tip" that police had used a DED unlawfully, Moss said the ACLU filed its first Freedom of Information Act (FOIA) request in 2008 to learn the policies and practices surrounding the extraction device.
The police did not offer answers. Instead, they told the ACLU it would need to pay more than $544,000 to retrieve the records and reports it had asked for. Over the past few years, Moss said the ACLU has tried to work with the police to narrow the request and lower the cost, but with little success.
"Both federal and state laws make it very clear that you can't conduct surveillance of phones or these kinds of electronic devices without a search warrant," she said, adding that if the device is being used without a warrant or people's knowledge, "There's some serious constitutional violations here."
When asked for details about the evidence indicating the misuse of the DEDs, Moss declined to elaborate.
"We have credible information that they were being used during routine stops without a warrant," she said. "And their response that information would cost half a million dollars suggests that there was some widespread use."
Michigan Police: Reports About Devices Used During Routine Stops Is 'Inaccurate'
But Michigan State Police spokeswoman Tiffany Brown said the devices have never been used to take personal cellphone information from citizens during routine stops.
"The information that's been floating around that these devices have been used during routine traffic stops, that information is just inaccurate," she said.
Since the state got roughly six DEDs in 2006, Brown said, they have been used by specialty teams in high-level cases that require digital forensics methods -- for example, a child pornography case in which officers would need data from a suspect's computer and cellphone.
When asked why the cost of meeting the ACLU's FOIA requests were in six digits, Brown said that was what it would cost to have several employees, working full-time, assemble documents from a five-year period.
She also said that in the five years that the state has owned the extraction devices, it has not received any citizen complaints or been named in any lawsuits.
Cellebrite did not respond to requests for comment from ABCNews.com, but on its website, the company says the devices, which can override user lock codes and retrieve deleted data, are used by military, law enforcement and intelligence agencies around the world.
When asked about the ACLU's next steps, Moss said, "We are evaluating. ..."There are a lot of unanswered questions."