The problem that arises within police culture is the us vs. them mentality that develops. The code of silence has often been talked about where an officer is expected to cover up any wrongdoing of another officer out of a sense of loyalty. Some see it as necessary to do the job. Others see it as a loss of compassion and the human touch needed to be the protectors the job commissioned them to be. In the mix officers seem to forget that they are supposed to be the helpers and the mediators, not the jury and the judge.
Many officers started on their career path out of a sense of duty and service. They want to protect and serve the people. Officers often go in expecting to spend a career as a helpful counselor, logical mediator, local hero and generous humanitarian. They often go into circumstances where they need to act as negotiators to help people in emotionally fueled situations.
Because of the way police officers have to entrust each other with their lives, a brotherhood type mentality is often adopted. Officers view each other as brothers in arms and take on roles of big brothers or uncles to new officers. Every time they go into a situation, they need to feel they can trust any other officer with their own life. That kind of risk drives the need to make the group trustworthy like a family.
Once an officer is out in the field they soon realize the power of their discretion. They can enter into a situation and be in control of what happens to the people involved. After years of responding to situations where people do not view them as the heros they signed up to be this aspect usually is what is left after the dream has died. It takes a special kind of person to avoid letting the job become about the power.
When the officers start seeing their co-workers as family and society as the enemy, what chance is their that the common person will be treated fairly? Mostly personal character determines who will remain the helpful good cop. The officer with a conscience and often an internal struggle with the evil they have seen can hold on to their ideals. While the selfish cop will use the job to punish those who don't show them respect, to decide who is guilty or unworthy of help and who uses the job to take from people.