The legal system is divided into two areas: civil law and criminal law. Separate courts govern (control) these two areas of the law.
One of the most confusing things about the legal system is the difference between civil cases and criminal cases. In domestic violence situations, there may be both civil and criminal cases occurring at the same time as a result of the same violent act. You may want to pursue both civil and criminal actions for maximum protection. The major differences have to do with who takes the case to court and the reason for the case.
In a civil domestic violence action, you are asking the court to protect you from the person abusing you. You are not asking the court to send that person to jail for committing a crime. However, if the abuser violates the civil court order, s/he may be sent to jail for the violation. In a civil case, you are the person bringing the case against the abuser and (in most circumstances), you have the right to withdraw (drop) the case if you want to.
The criminal law system handles all cases that involve violations of criminal law such as harassment, assault, murder, theft, etc. A criminal complaint involves the abuser being charged with a crime. In a criminal case, the prosecutor (also called the district attorney) is the one who has control over whether the case against the abuser continues or not. It is the county/state who has brought the case against the abuser, not the victim. It is possible that if you do not want the case to continue (if you do not want to “press charges”), the prosecutor might decide to drop the criminal charges but this is not necessarily true. The prosecutor can also continue to prosecute the abuser against your wishes and could even issue a subpoena (a court order) to force you to testify at the trial.