Serpico has some ideas on how to tackle police corruption:
1. Strengthen the selection process and psychological screening process for police recruits. Police departments are simply a microcosm of the greater society. If your screening standards encourage corrupt and forceful tendencies, you will end up with a larger concentration of these types of individuals;
2. Provide ongoing, examples-based training and simulations. Not only telling but showing police officers how they are expected to behave and react is critical;
3. Require community involvement from police officers so they know the districts and the individuals they are policing. This will encourage empathy and understanding;
4. Enforce the laws against everyone, including police officers. When police officers do wrong, use those individuals as examples of what not to do – so that others know that this behavior will not be tolerated. And tell the police unions and detective endowment associations they need to keep their noses out of the justice system;
5. Support the good guys. Honest cops who tell the truth and behave in exemplary fashion should be honored, promoted and held up as strong positive examples of what it means to be a cop;
6. Last but not least, police cannot police themselves. Develop permanent, independent boards to review incidents of police corruption and brutality—and then fund them well and support them publicly. Only this can change a culture that has existed since the beginnings of the modern police department.
The whole article from Politco is an interesting read.