Commonwealth's attorney is the title given to the elected prosecutor of felony crimes in Kentucky. Other states in the U.S. refer to similar prosecutors as district attorney or state's attorney.
The prosecution is the legal party responsible for presenting the case against an individual suspected of breaking the law, initiating and directing further criminal investigations, guiding and recommending the sentencing of offenders, and are the only attorneys allowed to participate in grand jury proceedings.
A commonwealth's attorney is the highest law enforcement official in his or her jurisdiction and in many jurisdictions supervises a staff which includes a chief deputy commonwealth's attorney, deputy commonwealth's attorneys and assistant commonwealth's attorneys. The prosecutors decide what criminal charges to bring, and when and where a person will answer to those charges. In carrying out their duties, prosecutors have the authority to investigate persons, grant immunity to witnesses and accused criminals, and plea bargain with defendants.
A commonwealth's attorney is a constitutional officer, which means that the job is established in the state's constitution which defines the position, the broad powers of the elected officeholder and the requirement that every county and every city be served by a commonwealth's attorney. Certain cities in Kentucky are independent jurisdictions (hence the term "independent city," a designation conceptually similar to that of cities having imperial immediacy under the Holy Roman Empire) and not part of any county.
The role of commonwealth's attorneys, district attorneys, and state's attorneys should not be confused with the role of a county attorney or city attorney whose authority is usually limited by individual state constitutions to non-felony infractions or misdemeanor cases.
Commonwealth's attorneys are elected in their respective jurisdictions for terms of six years.