A moment with a search engine will turn up story after story of people in uniform putting their lives on the line to help others.
Personally, I think they're heroes because they're people just like you and me who are willing to risk their lives to help other people. At least most of them are, I believe.
Law enforcement is necessary(strictly, a crime investigation unit, a force capable of handling armed/bomb situations, etc.) but something has seriously gone wrong with the way it’s been implemented in many cities, counties, and states.