The American Civil Liberties Union has called on Michigan State Police to account for several pieces mobile hardware in its possession that can quickly download cellphone data without the owner's knowledge.

“With certain exceptions that do not apply here, a search cannot occur without a warrant in which a judicial officer determines that there is probably cause to believe that the search will yield evidence of criminal activity,” ACLU Staff Attorney Mark Fancher wrote in an April 13 letter to Col. Kriste Etue, director of the Michigan State Police.

“A device that allows immediate, surreptitious intrusion into private data creates enormous risks that troopers will ignore these requirements to the detriment of the constitutional rights of persons whose cell phones are searched.”

The inquiry is related to the acquisition by Michigan police of devices from Cellebrite, a maker of mobile forensics hardware for extracting data in the field. Among other things, the company advertises that its products can be used to “insure that a suspect's phone can be examined before the individual has a chance to destroy or erase data.”

Fancher said ACLU officials want to ensure use of the devices is consistent with the Constitution's Fourth Amendment, which protects citizens against unreasonable searches and seizures.

The increased use of mobile devices, particularly smartphones, makes it easier than ever for the government to get their hands on gigabytes worth of sensitive information, including text messages, email, appointment calendars and contacts. On Wednesday, researchers reported that Apple iPhones and iPads log detailed information on users' every move and store it in a device file that's easily readable to anyone with physical access to the device.

There doesn't appear to be any way to turn the tracking off, and the only way to scrub the device clean is to jailbreak it and regularly delete and wipe the file. (The file is also stored on computers that sync to the iDevices.)

The letter comes two and a half years after the Michigan branch of the ACLU filed its first Freedom of Information request seeking documents about police use of the Cellebrite devices. Michigan State Police officials have refused to honor the request unless the civil rights organization first pays a $272,340 deposit, which they claim represents half the cost of supplying the documents.

The ACLU claims it has since filed more than 70 separate FOIA requests attempting to narrow the request, but has yet to obtain the documents it seeks.

Among other things, Fancher called on Michigan Police to explain how and when the devices are used in the field, whether citizens are informed of their use, and whether officers first obtain search warrants.

“Law enforcement officers are known, on occasion, to encourage citizens to cooperate if they have nothing to hide,” Fancher wrote. “No less should be expected of law enforcement, and the Michigan State Police should be willing to assuage concerns that these powerful extraction devices are being used illegally by honoring our requests for cooperation and disclosure.” ®