Since the mid-1980s the Stockholm Metro has been seriously affected by graffiti. Previously, a train on which graffiti had been painted could remain in service for weeks, and graffiti could remain in place at stations for months, if not for years. Nowadays, however, trains with graffiti are immediately taken out of service, and graffiti at stations is regularly cleaned up within a few days. The cost of graffiti and other types of vandalism is calculated at an annual cost of around 100 million Swedish crowns.
During the 1990s, the Stockholm Transit System (SL) started to employ personnel from various private security firms. Some of these security firms have been accused of using unlawful methods such as plain clothes guards and of brutal treatment of arrested vandals. Since 2005, the Stockholm police has assigned a special task force (Klotterkommissionen) to deal with the problem.
