What is meant by the slippery-slope model of economic corruption is that the first illegal acts committed by a police officer are minor, easy to justify. It becomes easier to commit more serious wrongful acts after person has committed minor acts of corruption. The slippery-slope metaphor is a powerful way to think about police corruption. It recognizes the importance of police peers in encouraging corruption and the role played by the secretive elements of police culture. Police corruption and reform have been intertwined issues in the history of policing in the United States. Grafting and extortion were principal forms of corruption at the beginning of the twentieth century, and doing something about them has been central to police reform. The professionalism movement, though successful in many ways, had some outcomes that were not quite as intended. The magic pencil is a form of noble-cause corruption, in which police officers write up an incident in a way that criminalizes a suspect.