As has been said before, the law in Miami and the USA is applied to the extreme. There are three corporations to enforce the law there: the county sheriffs, the highway patrol, and the city police. All people (locals and tourists) are under their watch, who are generally very friendly and helpful, always promoting the idea of a touristy and relaxed Miami. You can count on them if you need any help or information. For the smooth running of your trip, just avoid contradicting them or disobeying the established rules.