The Constitutional Court in Karlsruhe thus rejected a former left-wing militant's appeal to his 1999 conviction for several bomb attacks. The man had been sentenced to 13 years in jail partly based on evidence police collected by tracking his movements using a GPS device secretly attached to his car. The court ruled that keeping tabs on suspects' movements did not normally invade their privacy.

The judges did, however, add that lawmakers should prevent "all round surveillance," keeping an eye on technical developments and ensuring that public prosecutors are informed in all cases to prevent suspects from being the subject of uncoordinated observation from different law enforcement agencies at the same time.

German Justice Ministry Otto Schily welcomed the ruling. "The Constitution Court confirmed a significant instrument for police investigations and safeguarded use of the most modern technical methods for fighting crime," he said in Berlin. Justice Ministry State Secretary Hansjörg Geiger praised the court for approving "weapon parity" between criminals and investigators.

Avoiding 1984

But many years have passed since GPS was used in the case the Karlsruhe judges examined and technology has made leaps and bounds, pointed out data protection specialist Frank Rosengart from Berlin's Chaos Computer Club (CCC).

"GPS is no longer necessary, except for when the suspect really doesn't have a telephone with him or it's always turned off. Otherwise, the person's location can be much better determined through his mobile phone," Rosengart said, adding that GPS is rarely used by police forces.

Berlin's police already use so-called silent text messages to locate suspects, for which the CCC awarded the force its Big Brother Award last year. Data protection experts should focus their attentions on tracking via mobile phones, Rosengart said.

"At the moment only the legal situation prevents things from being transposed as George Orwell described in '1984,' his gloomy vision of a surveillance state," Rosengart said. "The technical means are largely there. Luckily there are still quite clear limits."