Criminal cases begin with a criminal complaint filed in misdemeanour crimes, or indictments in felony cases where grand juries are used. After arrest, the defendant is arraigned before a judge or magistrate, a plea is taken, and the case is bound over for trial. A preliminary hearing is usually held, where a judge decides only if sufficient evidence exists to justify a trial. A state prisoner ordinarily uses a writ of habeas corpus in attempting to get his or her case into the federal courts. To do this, a violation of a right under the U.S. Constitution must be shown. Because there are very few violations (or errors) of this type, few habeas corpus hearings are granted.