Law is made by both the legislature and the courts. This occurs at both the state and federal levels.
Law made by a judge in deciding cases is called common law.
Decisions made by judges may be written and published in books and may be relied upon by lawyers and others in cases with similar facts. Judges or courts only have the power to make laws regarding cases presented before the court for a decision. Where legislatures have passed laws, courts must follow their laws unless the law violates the constitution. In many situations, when the law is unclear or does not adequately cover the facts of a case, the court will have to interpret the law. Laws must not violate the constitution.