Duty to intervene: Floyd cops spoke up but didn’t step in

This combination of photos shows Derek Chauvin, from left, J. Alexander Kueng, Thomas Lane and Tou Thao. Chauvin is charged with second-degree murder of George Floyd. Kueng, Lane and Thao have been charged with aiding and abetting Chauvin. (Hennepin County Sheriff's Office via AP)

Minneapolis was among several cities that had policies on the books requiring police officers to intervene to stop colleagues from using unreasonable force, but that didn’t save George Floyd and law enforcement experts say such rules will always run up against entrenched police culture and the fear of being ostracized and branded a “rat.”