A bench warrant is a type of arrest warrant which is issued by a judge or court, most typically when someone fails to comply with a court order or requirement. When a bench warrant is issued, law enforcement have the authority to pick up the subject of the warrant and bring him or her to court to address the charges of a bench warrant; the subject is literally brought before the judge's bench to respond to the warrant. Bench warrants are often used as tools for fighting contempt of court, a willful disregard of a court order. Some judges are more prone to issuing bench warrants than others; as a general rule, you should avoid contempt of court anyway, as the penalties can be severe.
One example of contempt of court is a failure to appear in response to a jury summons. A judge can issue a bench warrant which obligates someone to come to court and answer contempt charges, although many judges do not want to deal with the paperwork of issuing bench warrants for people who fail to appear for jury duty. More commonly, a bench warrant will be issued to someone who did not show up for a scheduled court date, or for someone who decides to disobey a subpoena to testify in a case.
In order to file a bench warrant, a judge must generally demonstrate a personal knowledge of the contempt which instigated the warrant. Otherwise, a judge must wait for someone to file an affidavit requesting a bench warrant. For example, if person N fails to pay child support to person Y, person Y's lawyer can file an affidavit for a bench warrant to request the presence of person N in court. Person N must explain why he or she failed to pay child support at this court appearance.
A bench warrant is slightly different from a more general arrest warrant. A warrant for arrest is issued when a law enforcement agency has reason to believe that someone has been involved in a crime. For example, an arrest warrant will be issued by a court for someone who is accused of murder so that he or she can be indicted and tried. Typically, someone can pay bail to get out of jail after an indictment hearing has been held, while the subject of a bench warrant may not be allowed to pay bail if the court determines that the person needs to be held in jail, since she or he is deemed a flight risk.