What is sometimes called the administrative state is composed of agencies in the executive branch that implement broad, general statutory commands, sometimes as vague as "public interest, convenience and necessity" or "just and reasonable" rates, either by promulgating regulations having the force of law, or by developing a body of case law through adjudication. Their findings of fact and conclusions of law are not reviewed de novo by the Article III courts but receive judicial deference. When the agency has a multi-member head, Congress can limit the president's ordinary power under Article II to remove subordinates. These law making and fact finding functions are commonly referred to as quasi-legislative and quasi-judicial.

The administrative state goes back to 1887, when Congress established the Interstate Commerce Commission to regulate railroad rates. It mushroomed under the New Deal. It was created in response to the growth of a consolidated national economy dominated by multi-state corporations whose operations were too large and widespread to be effectively regulated at the state level, and which created dangerous, exploitative concentrations of economic power. The Great Depression was the crisis of the largely unregulated national economy, and the flowering of the administrative state was the response.