My first question to you is are you talking about police corruption in general as in all or any place in the world, or do you plan to choose this country and one or two cities within this country? If you plan to discuss this topic without narrowing your focus, this essay will be difficult to write. Think about what you want to narrow in on--a specific city, management corruption, police on the street corruption, or how any corruption affects the city or country in which it takes place. For example, in Bolivia, South America, you can usually get a traffic ticket dismissed by paying off the officer who stopped you. With the lawlessness of the drug cartels affecting the country of Mexico and how the world sees this country, tourism is dropping because of the fear of violence. In this country, efforts have been made in many cities to clean up corruption. In the 1930's, St. Paul, Minnesota was a playground for the mob as many vacationed there and were protected by the local police. Since then, much has been done to make St. Paul an exemplary city with an honest police force. You just have to narrow your focus so that it's what you really want to talk about and then outline and write your essay.