Studies of police activities have shown that members of minority groups are disproportionately singled out for searches. In some jurisdictions, this has been common practice, the data show. This has led some lawmakers to conclude that such tactics constitute harassment, and they have introduced legislation to ban racial profiling.

A study by Steve Cooper, program coordinator of criminal justice at American Military University, found that race is a factor in police activity, along with other factors.

A Pennsylvania police chief told Cooper, "I believe a legitimate traffic stop can be made on the basis of viewing a black individual in a white neighborhood in a fancy car, wearing a multitude of gold chains, wearing sunglasses."

Cooper comments, "His first indicator of potential criminality was the race of the individual, but the other factors (gold chains, white neighborhood, etc.) also appear to be influential variables."

Cooper points out that racial profiling may be responsible for the disproportionate number of blacks being arrested for drug offenses, though "blacks and whites use drugs at approximately the same rate."

Cooper says racial profiling is a factor in "the alarming number of minorities who are in the criminal justice system... As many as one in three, and even as high as one in two black men in certain areas of the country are under some form of criminal justice control... For every black man enrolled in a degree program in California, there were five black men under some form of criminal justice control."

Cooper says that journalists should be suspicious of a police department if it refuses to supply data on stops and arrests by race. For example, a study of vehicle noise violations has found that African-Americans were more likely than whites to be cited and arrested.