A protection racket is a scheme whereby a criminal group provides protection to businesses through violence outside the sanction of the law. Through the credible threat of violence, the racketeers deter people from swindling, robbing, injuring, sabotaging or otherwise harming their clients. Protection rackets tend to appear in markets where the police and judiciary cannot be counted on to provide legal protection, either because of incompetence (as in weak or failed states) or illegality (black markets). Protection rackets are not the same as extortion rackets. In an extortion racket the racketeers agree not to attack a business. In a protection racket the racketeers agree to defend a business from any attack. However, they may threaten to attack or attack the business if it refused protection. Certain scholars, such as Diego Gambetta, classify criminal organizations engaged in protection racketeering as mafia.