Hi,
I do now know what the use of force laws are like in Brazil.
Here it Canada a person is held criminally responsible for all excessive force used in any situation. During recent training I was informed of an occurrence in 1999 where an RCMP Officer "double tapped" a violent, impaired suspect at a police station during a struggle for the officers pistol. The officer was later convicted of excessive force (manslaughter with a firearm) in his 3rd trial (after 2 hung juries). It was decided that the first round was justified and had removed the threat but that the quick, lethal second shot (within 2 seconds of the first) was excessive. The question for the jury became, who had control of the pistol when the second shot was fired? A brief discription of this case can be found here
http://www.rbta.net/ferguson.html . This case later went to the Supreme Court of Canada concerning the sentence imposed by the lower court.
I am not making any judgement in this case, only saying that you will be held responsible to justify all force you apply, including every round you fire in a defensive situation.
Mike