I agree Taln. Treat them how you want to be treated. Of course there are jerks in every profession. I had a Highway Patrolman who pulled me over weekly on the way to work to "check the window tinting". I was always polite, even when I asked for his name and badge number to report him for harassment. He left me alone after that. I think I was profiled since I was Hispanic and driving a nice car (drug smugglers do this). But most are nice.
The Japanese police were always very polite. They even put everything back where it was when they searched my apartment.