Obama cracks down on abuses by big-city police departmentsBy Justin Elliott AP/Julio Cortez Thomas Perez, assistant attorney general for the Civil Rights Division, center, talks about a federal investigation of the Newark Police Department during a May 9 news conference with Newark Mayor Cory Booker, far left. In a marked shift from the Bush administration, President Obama's Justice Department is aggressively investigating several big urban police departments for systematic civil rights abuses such as harassment of racial minorities, false arrests, and excessive use of force.In interviews, activists and attorneys on the ground in several cities where the DOJ has dispatched...