While the most prominent special prosecutors have been those appointed since the 1870s to investigate presidents and those connected to them, the term can also be used to refer to any prosecutor appointed to avoid a conflict of interest or appearance thereof. The concept originates in state law: "state courts have traditionally appointed special prosecutors when the regular government attorney was disqualified from a case, whether for incapacitation or interest." Because district attorneys' offices work closely with police, some activists argue that cases of police misconduct at the state and local level should be handled by special prosecutors.