Excessive force on the part of the police was among the major causes of the 1967 Detroit riots. In a Detroit Free Press survey in the aftermath of the riots, residents identified police harassment and brutality as the number one problem that they faced in the period preceding the events of 1967. During the 1960s, the so-called “Big Four” or “Tac Squads” operated on the streets of Detroit. The elite, four-man units developed a reputation among black Detroiters for treating African American residents unfairly and even violently. The police frequently stopped young blacks and demanded to see identification. Often, these stops resulted verbal abuse, with the police calling young black men “boy” or “nigger.” While most encounters did not proceed beyond this humiliating verbal abuse, if an African American could not produce proper identification, the stop could result in an arrest or even police violence. In some extreme cases, such police brutality resulted in injury or even death of those detained. For example, in 1962, when a black prostitute named Shirley Scott attempted to flee from the back of a patrol car, Detroit police shot her in the back. Among the other notable case of police brutality in the years leading up to the riots were the severe beating of another prostitute, Barbara Jackson, in 1964, and the beating of Howard King, a black teenager, for allegedly disturbing the peace.

African Americans in Detroit also resented police raids on the after-hours drinking clubs known as blind pigs. These establishments had been an important part of African American social life in Detroit for decades, dating backed to the Prohibition period. In addition, these clubs were a response to the fact that many Detroit restaurants and bars discriminated against African Americans.

Many blacks in Detroit also resented the aggressive and sometimes violent way in which the police handled the issue of prostitution in the city's African American ghetto. African American leaders had complained that the police did little to prevent white male clients from exploiting black female prostitutes. However, in the weeks leading up to the riots, police launched an aggressive campaign to limit prostitution in the area where the riots erupted. When a prostitute was killed on July 1, rumors circulated that the police had killed her. The police in turn claimed that local pimps had killed the woman.

There were some unsuccessful attempts to reform the Detroit police before the riots. Police commissioner George Edwards did try to recruit and promote African American police officers. However, he refused to establish a civilian police review board, which upset the African American population. At the same time, by working to actively discipline police officers guilty of brutality, Edwards often lost the support of many on his force and incurred the wrath of many white Detroiters who Page 994  |  Top of Articlecame to view him as too soft on crime. Outside groups also found that despite such attempts at reform, the Detroit police was indeed a racist organization. The Michigan Civil Rights Commission conducted a study in 1965 that the Detroit police recruited “bigots” and reinforced racial discrimination through its value system. Furthermore, President Lyndon Johnson's Commission on Law Enforcement and Administration concluded that 45 percent of Detroit police officers working in predominately African American neighborhoods were “extremely anti-Negro.”