One in five prison beds in Germany are empty. The figures from German juvenile offenders' institutions are even more striking: the rate of youth crime fell by half between 2007 and 2015. This phenomenon is only partly linked to the fact that the population is ageing. German criminologists believe a ban on corporal punishment has had a positive effect on the country's youth. Our correspondents report. A programme prepared by Patrick Lovett and Gaëlle Essoo.