Editing Discworld (section)

===The Thieves' Guild===
''"Acutus Id Verberat"'' ("Whip it Quick")

Established by Lord Vetinari as a way to regulate crime in Anhk-Morpok. License-carrying thieves are legally able to steal, mug, rob, burgle, and otherwise shake down the populace, to a carefully measured and reasonably applied degree. Victims who play along are well-treated, given a notarized receipt, and a period of grace before another visit. One may exempt themselves from such meetings with proactive "charitous" donations to the Guild - drawing humorous parallels with tax collectors.

Crime dropped swiftly after the creation of the Thieves Guild, mainly due to providing most of the cities gangs and career criminals with a stable income, one that they viciously protect from any unlicensed competitors trying to operate in their turf.

Surprisingly, this is not that far off from history. In short, if the situation is lawless (like how things were in large preindustrial cities) the local gang of thieves running a protection racket can be the best defense against theft. Minor shakedowns every month for a few pennies are easier and in the long term more profitable than robbing people blind and ruining them, especially when you actually catch criminals who were threatening the clients in the protection racket.