1. Inhalt
  2. Navigation
  3. Weitere Inhalte
  4. Metanavigation
  5. Suche
  6. Choose from 30 Languages


German states join forces to monitor convicted criminals

A number of German states have pledged to work together to monitor convicted criminals ordered to wear electronic tags. But systems for keeping an eye on offenders go beyond the traditional ankle bracelet.

An electric tag being wrapped around a leg

In certain states electronic tags will be centrally monitored

The German states of Baden-Württemberg, North Rhine-Westphalia and Mecklenburg Western-Pomerania joined Bavaria and Hesse on Monday in agreeing to work together to monitor electronic tags worn by ex-offenders.

Beginning in early 2012, a joint monitoring center in Bad Vilbel, near Frankfurt, will track several hundred ex-offenders wearing the electronic ankle bracelets.

Bavaria and Hesse were the first to sign the cooperation agreement in May. Germany's remaining states are expected to join at a later date.


Electronic tags can eliminate the need for a lengthy detention period for criminal suspects who are awaiting trial, and can also be used to help authorities reintegrate convicted offenders back into society.

"It's often the case that the offender who served time in prison is also the main breadwinner of a family," said Götz Stamm, representative of the company 3M/ElmoTech, the world market leader for the electronic monitoring systems. "The family's entire social status can depend on the fate of this one person. Worst-case scenario, the whole family can become reliant on social help - which could be avoided."

A man holds up an electronic tag

The electronic tag is roughly the size of a sports watch

The electronic tags give offenders who are allowed to work a job outside of prison a chance to do so, and these systems can monitor their location at all times.

The actual electronic tag is an encapsulated waterproof transmitter which is fastened around the offender's ankle by a strap. A receiver is installed in the subject's house which, within a certain range, will pick up signals from the ankle bracelet. The receiver can then transmit the data to a central server.

"This is done in consultation with a specific timetable or according to the conditions set by the court for the subject," said ElmoTech's Katrin Hemsing, who was involved with the introduction of the electronic tags in Hesse.

Central regulation

But it's not just offenders under house arrest who are monitored in such a manner. Electronic tags can be used to sound an alarm when offenders are at home and they should be elsewhere, like a court-ordered doctor's appointment or therapy session.

A breathalyzer

Breathalyzers are an alternative monitoring method

In these cases the electronic tag operates with a second apparatus so the offender can be monitored beyond the limits of his house. The tag then uses the GPS navigation system to transmit location data to the monitoring center. Exclusion zones can then be defined, such as in cases where a court has forbidden a violent criminal from approaching his victim.

For example, in a case where an offender had attacked his ex-wife, he would be prevented from going near her house or workplace.

"The aggressor also knows that he must not approach these exclusion zones," said Hemsing. If he should still cross these limits, an alarm will sound at the monitoring center.

The device won't just alert the authorities when an individual has crossed into a restricted zone, but also the offender themselves, often with something like a vibrating alarm. The victim would also be alerted either by text message, or a beep or vibration on her own corresponding device.

Biometric recognition

Electronic tags aren't the only tool used to monitor convicted criminals. An breathalyzer can be employed in cases where the offender committed a crime under the influence of alcohol.

Just like the receiver of the ankle bracelet, the device is installed in an offender's home. He or she is then required to blow into a breathalyzer for random tests or at specific intervals.

The offender doesn't necessarily have to abstain entirely from alcohol, as the device can be set to allow the consumption of varying amounts. "Depending on how the alcohol level is set on the device, the offender may have to remain completely sober or he could be allowed to drink one beer a day" said Hemsing.

The breathalyzer isn't easily fooled. If the offender tries to convince a sober friend to blow into the breathalyzer, the camera on the device is able to use face recognition to detect the difference.

Screenshot of face recognition while using a breathalyzer

The face recognition cameras compare the person blowing into the breathalyzer with a stored photo

Voice recognition can also be used to monitor convicted felons. A judge could rule, for example, that a football hooligan must stay at home during soccer matches. Rather than employing the use of an electronic tag to ensure that he stays at home, the hooligan could instead receive calls from an automatic computer system which will confirm his location.

The offender would be called at random and asked a varying set of questions. The unique frequency of his voice means he can't just ask his neighbors to sit by the phone and answer on his behalf. The systems works almost like an acoustic fingerprint.

Escape is possible

But electronic monitoring systems do have their failings. According to Götz Stamm, they only make sense if the convicted person is willing to cooperate with the authorities. It is, in fact, possible to cut off the electronic tag with a simple cable cutter.

If the offender does manage to remove the bracelet, however, the system will immediately sound an alarm, allowing police to respond quickly. Probation officers and police can also use special GSM receivers with which they can track the movements of their charge.

And should perpetrators be caught manipulating the monitoring systems, their freedom would come to an abrupt end and they'd be sent straight back to prison.

Author: Fabian Schmidt / ccp
Editor: Martin Kuebler

DW recommends