Historically, criminal justice system targeted at the elimination of crimes and establishment of social order. Nonetheless, as a rule it was and still is severely criticized to the extent that some specialists like Reiman estimate that the existing criminal justice system is basically the ideological tool and product of the capitalist system that does not necessarily mean justice literally.
In fact, such a point of view is quite reasonable and is based on the idea that the existing criminal justice system is not as independent as it is supposed to be since ideally justice as judicial power at large is supposed to be separated from legislative and executive power.
However, in the modern capitalist system the criminal justice system turns to be a tool in the hands of political and economic elite that actually rules the political and socio-economic life of the country and thus imposes its ideology, i.e. the ideology of capitalism, to the whole nation.
In such a situation, a state turns to be the system of oppression of masses of people in the hands of political and economic elite, while the criminal justice system, being a part of the state, is just one of the mechanisms by means of which the ruling elite oppresses the deprived classes.
At the same time, the oppressed people are unconscious of this fact, instead they are deceived by the existing stereotypes and biases and rather prefer to obey to the existing laws of the capitalist society established by the privileged classes, or elite than attempt to really change the situation.
On the other hand, the capitalist system is based on the oppression of lower classes by the ruling elite leading to the growing poverty and deterioration of the position of the lowest layers of society contributing to the growing rates of crimes among the poorest people. However, their crimes are not viewed as a naturally attempt to survive or improve the life by means of changing the unjust capitalist system. Instead, their crimes are viewed as acts of their evil nature or will but not as the result of their deprived socio-economic status.
Moreover, the punishment for their crimes, being one of the basic concepts of the criminal justice, does not target at the improvement of the life of society at large or correction of criminals but it rather targets at the oppression of any attempt of rebellion in order to keep the social order and preserving the capitalist system from changes.
In such a situation, capitalist system, being beneficial for economic and political elite, uses the criminal justice to preserve and improve its position by means of oppressing lower classes, which are lacking of the conscience of the oppressive function of the justice system that deteriorates their position, in contrast to the position of the elite.

Bibliography:
1. Reiman, J. The Rich Get Richer and the Poor Get Prison. New York: Allyn and Bacon, 2006.