A judicial hearing happens before a civil or criminal trial and can include one-sided (ex parte) hearings, such as the justification for issuing a restraining order, or adversarial hearings, where both sides are heard. Preliminary hearings take place before a person has been charged with a crime and a judge or magistrate decides if that person should be held in jail or released on bail, while detention hearings are used to decide if a juvenile should be kept in police custody. Suppression hearings are called when a lawyer does not want to have certain evidence (often not germane to the case or otherwise collected illegally), used in a case.
An administrative hearing helps determine rules as well as certain legal cases, as decided by state and federal offices. They are typically found to bring public opinion to light on issues that affect the public, such as when a federal agency like the Environmental Protection Agency might want to change a policy. They are also used when a person has broken rules or laws that are set by a federal or state agency.
A legislative hearing are also held by state and federal offices; they are also a way to find facts and to air public opinion as laws are analyzed for potential change and unethical or illegal behavior is analyzed. The state legislature and U.S. Congress handle these public hearings, and may punish those found guilty through the decisions of state and/or federal ethics committees.