Dirty cop

Police corruption is a form of police misconduct in which law enforcement officers end up breaking their political contract and abuse their power for personal or departmental gain. This type of corruption can involve only one officer, or it can involve a group of officers. Internal police corruption is a challenge to public trust, cohesion of departmental policies, human rights and legal violations involving serious consequences. Police corruption can take many forms.

Soliciting or accepting bribes in exchange for not reporting organized drug or prostitution rings or other illegal activities and violations of law, county and city ordinances and state and federal laws.

Flouting the police code of conduct in order to secure convictions of civilians and suspects—for example, through the use of falsified evidence. There are also situations where law enforcement officers may deliberately and systematically participate in organized crime themselves.

Selective enforcement

In most major cities there are internal affairs sections to investigate suspected police corruption or misconduct, including selective enforcement, but there are situations where Internal Affairs also hides departmental and individual corruption, fraud, abuse and waste by individual officers, groups of officers or even unwritten departmental policies. There are also Police Commissions who are complicit in the same cover-ups, often to hide internal and departmental problems, both from public view, and also from inter-departmental reviews and investigations. Certain officers can be fired, then rehired by petition after they accrue enough signatures, often from the very criminals and violators from whom corrupt officers have garnered previous favors in exchange for officers "turning a blind eye", resulting in selective enforcement of violations being deterred, but actually promoted.

Similar entities include the British Independent Police Complaints Commission. Police corruption is a significant widespread problem in many departments and agencies worldwide.

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Wikipedia