Just a couple of examples (my personal experience).
One day I had serious traffic accident in the small sh@tty city at North Coast. The accident happened at 6 PM, and after PN involved in the case they wanted me to stay locked in their police station overnight. I tried to be friendly, but they did not want to let me go. Then I started to explain that I know some people who can help them to change their mind. I called my friends and my lawyer. After my lawyer explained something to officer on the phone, their faces changed from oligophrenic smile to sad look, and they waited more than 3 hours until the lawyer came there. In 5 minutes after he arrived I was a free person again. But if I had to choose "kiss the cop in the ass" tactics as ExtremeR suggested here, I could really spent the night in the cell with criminals.
Another day I had another problem, I don't want to write the full story here, but as a result of the story I met a fiscal adjunto accompanied by 3 police officers from very serious police department and waiting for me. And again, I could be arrested, but I started to explain that I'm not giving a f@ck because I know my rights and I know the right people. I called some of my friends, my lawyer came to resolve the situation, next day I visited fiscalia together with another lawyer (probably one of the best here), and all problems were resolved. But if I had to continue to stay calm and friendly, like ExtremeR suggested, I could be arrested for nothing by group of smiling idiots laughing at "stupid gringo".
To ExtremeR: I know what you say now that you are dominican and you know more.... but it's the same if I say that all dominicans only know how to dance bachata, how to be drunk all day at colmado and how to count 2+3 only using the calculator. Don't judge people if you don't know them in person. Most of dominicans are not friendly with logical thinking, so even if some people (I mean expats) know less than you about this country, they may know better how to act in some situations, because they think better and faster than average dominicans. However I am SO sorry that my opinion is so much different with yours and my advice here is DO NOT kiss the police in their asses and stand up for your rights. Of course you need to be polite, but never position yourself below them, because in this case they feel that they can do whatever they want to do with you, even if it's illegal.