What is law enforcement?
Many would go with the easy answer here, which is simply "enforcing the law". My experience as a law enforcement officer involved in many aspects of policing (including the hiring process) taught me pretty quickly that the answer is much more complex than this. A police job is about much more than driving around writing tickets and arresting people for violating the law.
The number one desirable trait in a law enforcement officer should be people skills. Unfortunately, the police hiring process lacks a good way to test for this. Most law enforcement agencies rely on psychological tests (a joke), polygraph (bigger joke) and the results of a poor background check that is outsourced to the lowest bidder. Nowhere in the hiring process is a person's reasoning skills or empathy tested, unless you count one of hundreds of multiple choice questions on a laughable psychological profile test.