Traditionally, U.S. voters have backed generous pay and benefits for the cops and firefighters willing to risk their lives to keep citizens safe. That was especially so after the deaths of many emergency workers in the September 11, 2001, attack on the World Trade Center in New York. But as economic conditions have worsened and many local governments have run into severe fiscal problems, that attitude has started to change. Since the 2007 recession, some cities have tried to roll back pension benefits and pay, among the most rigid and, in some cases, highest expenses in municipal budgets.