GPS ankle bracelets were introduced in the last decade to replace the original devices, in wide use around the U.S. since the 1980s, that require a land phone line. The bracelets alert a monitoring center when the person wearing it is away from the perimeter established by the court, usually their own home.

More sophisticated version of these devices have the same features as a cellular phone. They provide real time monitoring, with the capacity to record the location of the person wearing it---thereby allowing authorities to be warned if the suspect or convict is in a banned area or to confirm the individual is complying with his or her work, study, medical or other activities agreed with the court.

The high-tech surveillance capability of these devices represents an overstep of the state’s right to supervise a defendant .charged with a crime.

Via: The Crime Report:

When defense lawyer Fermín L. Arraiza-Navas sat down with a prospective client in San Juan, Puerto Rico last April, he casually asked the man about the Global Positioning System (GPS) ankle bracelet that he was wearing as a condition for his bail.

The reply was just as casual.

“They speak to me through that thing,” the man said.

It wasn’t the first time the lawyer encountered GPS bracelets with apparently extraordinary powers. He told the Puerto Rico Center for Investigative Reporting (CPIPR) that a previous defendant’s GPS ankle bracelet started to vibrate during a meeting with him.

But Arraiza-Navas decided this was more than a coincidence. He cancelled the meeting and filed a motion at the Puerto Rico State Superior Court in San Juan to have the device removed.

During the court hearing on the motion, his worst suspicions were confirmed.

A Corrections Department agent, who works at the Puerto Rico Pretrial Services Office’s monitoring center for defendants free on bail, placed a GPS ankle bracelet on the court podium and made a call from the device to a technician of the SecureAlert company, which provides them at a facility in Sandy, Utah.

The technician, who was addressed through the GPS ankle bracelet—which has a phone feature—testified that, although the device is supposed to vibrate when activated from Utah, the feature could be turned on without warning.