Agency officials act as lawmakers, law enforcers, and judges. Agency officials, therefore, possess a considerable amount of diverse authority. Much of that authority is discretionary. Agency officials do not have carte blanche authority, however, over the people and businesses they regulate. Many rules limit their discretion. Many of these rules come from legislative bodies and agencies themselves, but the fundamental law requiring fairness is the Constitution.

There are two constitutional fairness protections: due process and equal protection. The Fifth Amendment to the Constitution of the United States provides that “no person shall be deprived of life, liberty, or property without due process of law.” As is true of all of the rights in the Bill of Rights, the Fifth Amendment applies to actions of the federal government but not to state action. The Fourteenth Amendment, one of three post–Civil War Amendments, contains a second due process clause that that applies specifically to the states.

The precise meaning of “due process” is not self-evident and continues to evolve. Whether a fair process necessarily includes the other rights found in the Constitution, particularly those in the “Bill of Rights,” was unclear for years. Intended to prohibit states from discriminating against residents of other states, the Privileges and Immunities Clause protects the right to travel within the states and to take up residence and citizenship in another state.