Four common law doctrines—res judicata, collateral estoppel, equitable estoppel, and laches—may be applied by a reviewing court or administrative agency. The foundation of the four doctrines is the same: fairness and economy. All four doctrines were developed by courts in the context of judicial cases. The doctrines, however, are important to administrative law as well. Res judicata and collateral estoppel are applicable in administrative proceedings. The status of the applicability of equitable estoppel is not clear.

In the administrative context, the doctrines may play a dual role, one at the administrative level and another at the judicial review level. Collateral estoppel is similar to res judicata. Whereas res judicata prevents the relitigation of claims, collateral estoppel prevents the relitigation of issues. Be aware that the Supreme Court has recognized two significant exceptions to the standard res judicata and collateral estoppel rules.

First, in some instances identity of parties is not required. This is referred to as nonmutual collateral estoppel. Second, the Court has eased the common law restriction on who may assert collateral estoppel. At common law, only defendants could assert the doctrine. Equitable estoppel prevents parties from raising issues or asserting certain arguments.