In California, a former Bay Area police officer has escaped a full conviction for the 2009 killing of the unarmed African American passenger Oscar Grant. On Thursday, the officer, Johannes Mehserle, was found guilty of involuntary manslaughter but was acquitted on the more serious charges of second-degree murder and voluntary manslaughter, both of which carry longer sentences. Videotape of the killing shows Mehserle shooting Grant in the back while Grant lay face down on a subway platform. Members of Grant’s family immediately denounced the verdict. Scores of people were arrested in Oakland last night.