Supreme Court Justice wrote today, in Millbrook v. United States, that an intentional tort by a law enforcement officer does not fall under the exemption/immunity for federal employees.  Thus inmates may file suit for sexual abuse (as in the case).  The new interpretation encompasses all activities of law enforcement officers within the scope of their employment, not just the more limited “law enforcement activities.”

http://www.scotusblog.com/case-files/cases/millbrook-v-united-states/