CNN did a piece on ongoing study into with cop decision making and shootings and I thought at least one of the conclusions was interesting:
" (the study) ...volunteers of all races often viewed African American suspects as more threatening than white suspects, but that they may have subconsciously overcompensated because of that bias"
"The surprise is that they were more restrained in shooting African Americans than they were whites"
around 2:20
http://ac360.blogs.cnn.com/2014/09/2...iref=allsearch
Make of it what you will