The Law and Police in Brazil:

The Police service in Brazil has come under scrutiny from the media and human rights groups in the country over numerous cases of abuse and violence against suspects and obtaining bribes from criminals.

In all fairness the high crime rates in the country and willingness of criminals to use violence at slight provocation do not assist the situation and only increase the paranoia levels of police who do not really earn much from the job. Despite this local Police are helpful to tourists and the importance of tourism to the country means that there is increased security in tourist hotspots.

Reporting a crime at a police station can be a lengthy affair taking a few hours of your day. When caught up in a mugging with a knife or gun held to you, it is more logical to cooperate and offer no resistance which can cause you serious injury.

Drugs:

Marijuana use (though common amongst locals) can cause problems with the law and should be refrained while in the country.
Cocaine is a recent addition to the Brazilian drug scene and peddling especially in the slums of Rio and other major cities is a domain of young and violent street gangs.