Because they aren’t lawyers. They are police officers. Law school wouldn’t provide police officers with the kind of education they need to do their jobs. Most law students take one or two criminal law courses, one or two constitutional law courses and one or two evidence courses. Police would need to focus on understanding specific issues in these areas. These courses don’t go into the specificity police need. Police also need practical education, not the theoretical education of law school. In addition, their perspective is entirely different. Law students learn how to take a situation, identify the factual and legal issues and analyze them utilizing statutes and cases. Police officers are there to enforce the law. Police officers definitely need training. But it is not the same training that lawyers get or require.