Race and policing preoccupied Americans last week. The two shootings by police of black men in Louisiana and Minnesota rightly sparked outrage and protest across the country. Then came the racially motivated attack that killed five police officers during a Black Lives Matter rally in Dallas. Tensions between police and the African-American community were already high. For example, a June Gallup Poll reported that 67 percent of blacks believe that police treat African Americans less fairly than whites in their community. Is there any evidence of such biased policing? Unfortunately, yes.