Prosecution refers to the government's role in the criminal justice system. When criminal activity is suspected, it is often up to the government to investigate, arrest, charge, and bring the alleged offender to trial. Prosecutors are the lawyers who work for the government and who are responsible for developing and presenting the government's case against a defendant. Prosecutors may be called county attorneys, city attorneys, or district attorneys. The prosecutor is the opponent or "adversary" of the criminal defendant and his or her attorney; the two sides go head-to-head against each other in court. Because these public attorneys focus their energies on prosecuting criminal cases, they are generally very experienced in criminal law, and it is therefore essential to have an experienced defense attorney. Thus, in order to best preserve a criminal defendant's rights and strike a fair balance in court, representation by an experienced criminal defense attorney, particularly one knowledgeable in drunk driving law, is a must.