There are three main sources of law: common law, statutory law, and administrative law. Common law is based on previous court decisions, while most new law is statutory law passed by legislatures. Administrative law is made up of regulations from government agencies. New laws can be created when a bill is introduced in Congress, debated, and passed by both the House and Senate and signed by the president. Government agencies also create administrative rules and regulations and hold hearings to enforce compliance. Their power is balanced by statutory limits and oversight from the courts and elected officials.