The Military Police of Rio de Janeiro State (Portuguese: Polícia Militar do Estado do Rio de Janeiro) (PMERJ) like other military polices in Brazil is a reserve and ancillary force of the Brazilian Army, and part of the System of Public Security and Brazilian Social Protection.

[3] The primary mission of PMERJ is ostensively preventive policing for the maintenance of public order in the State of Rio de Janeiro.

Under the United Nations, in cooperation with the Brazilian Army, the Military Police of Rio de Janeiro State has served in Angola, Mozambique, East-Timor, Sudan, and Haiti.

[8] The Police Corps were created with the same structure as Brazilian Army, and to serve as reserve troops when necessary, under the provincial presidents' control.

The idea of a group of police officers who were specifically trained to work in extreme risk situations arose after the tragic outcome of the hostage incident in the Criminal Evaristo de Moraes Institute in 1974.

The BOPE is considered today one of the leading police forces to combat urban guerrilla in the world, that due to its wide experience gained in over 30 years of repression of drug traffickers and armed gangs in the favelas of Rio de Janeiro.

Beltrame has stated however that he believes based on analysis of crime data that only gang leaders higher in the hierarchy could reestablish in other favela communities (without Pacifying Police Units); and that lower level traffickers have a much harder time integrating into other geographic areas.

It was obvious early on that criminals were fleeing particular favelas before BOPE entered to establish a groundwork for a permanent police presence.

Exemplifying this point, one of Rio's newspapers reported on July 9, 2012 that groups of criminals fired upon police in different locations within the Complexo do Alemão on the same day that military forces completed their final withdrawal from the area.

Beltrame has stated that the main purpose of the Pacifying Police Units is more toward stopping armed men from ruling the streets than to put an end to drug trafficking.

A 2010 report by the World Organization Against Torture did note the drop in the homicide rate within Rio de Janeiro's favelas.

Colonel PM Cajueiro pointed out that the probability of being injured as a military police officer in the State of Rio de Janeiro is 765 times greater than in wars.

According to the ISP report, the chance of a casualty officer being killed by assailants (robbery crime) is 5877% higher than a person from another profession.

The primary vehicles of this police force featured in the film are mostly Chevy Blazers, Mazda 626, Volkswagen Passat station wagons, and Yamaha WR motorcycles.