The Ministry for State Security, known as the Stasi, which acted as East Germany's secret police and intelligence agency throughout the Cold War, used odour recognition to keep tabs on potential dissidents. They often collected the samples surreptitiously - breaking into homes to steal suspects' underwear, or by wiping down chairs used during interrogations. The samples were then stored in glass jars, each carefully labelled with details of whom the sample came from. Some of the jars are now on display at the Stasi museum in Berlin.
German authorities are compiling a database of human scents to track down possible violent protesters at the June G8 summit
There's precedent:
