Special prosecutor
A special prosecutor generally is a lawyer from outside the government appointed by an attorney general or, in the United States, by Congress to investigate a government official for misconduct while in office. A reasoning for such an appointment is that the governmental branch or agency may have political connections to those it might be asked to investigate. Inherently, this creates a conflict of interest and a solution is to have someone from outside the department lead the investigation. The term "special prosecutor" may have a variety of meanings from one country to the next, from one government branch to the next within the same country, and within different agencies within each government branch. Critics of the use of special prosecutors argue that these investigators act as a "fourth branch" to the government because they are not subject to limitations in spending or have deadlines to meet.
United States
Federal government
Attorneys in the United States may be appointed/hired particularly or employed generally by different branches of the government to investigate. When appointed/hired particularly by the judicial branch to investigate and, if justified, seek indictments in a particular judicial branch case, the attorney is called special prosecutor. When appointed/hired particularly by a governmental branch or agency to investigate alleged misconduct within that branch or agency, the attorney is called independent counsel. When employed by the state or political subdivision to assist in a particular judicial branch case when the public interest so requires, the attorney is called special counsel.