A gunman has opened fire on a car being driven by George Zimmerman, the man acquitted in 2013 of fatally shooting an unarmed black teenager that sparked protests and national debate about race.

Vigils and rallies will be held in 100 US cities this weekend to press for federal civil rights charges against George Zimmerman over the shooting of unarmed teenager Trayvon Martin.

The pretence of looking at the facts of a case may have its own prejudice, writes Neal Gabler