The monopoly of justice and its consequences

The action of punisher is becoming more and more frequent in large and small cities, and has been raising questions about whether or not what they do is right or wrong. And with the increase in urban violence and ineffectiveness of the police has to be made more litigated in debates and conversations.
The Brazilian defense and judgment system is a clear expression of what happens when there are no incentives to be efficient, since both are force monopolies established by the government. One of the best things provided is almost always decentralized and often with high competition, thus always improving any product.
In addition the action of punisher has been causing what is natural of any society, the creation of new services to supply those that already exist and do not please the population. If an individual decides for himself to do justice and in isonomy always respect thePNA (minimum ethical for a society does not collapse) there would be the possibility of any injustice, if by chance there is violation of the PNA the community itself would stop supporting such group, discouraging it.
In the end the action of the punisher comes to improve the security and reduce the fear of the social body, for sure a natural selection of the best would occur, always in search of the best and cheapest justice. In order to have a rise, there must be a "legalization" of the private police profession or sentinels.