That means you have a warrant for your arrest and you will be taken into custody if the police find you. Failing to appear at a required court appearance is contempt of court, especially if you are the defendant in a criminal charge. In some situations, failing to appear may result in a person forfeiting their bond. You'd get a chance to explain what happened to the judge. They essentially arraign the person on the failing to appear. In some situations, such as medical emergencies, etc., the judge won't impose any additional sanctions.
Answered on Jan 10th, 2013 at 3:16 AM