All agency actions can be classified as executive, quasi-judicial, or quasi-legislative. Because agencies are executive bodies, in most instances, they per-form executive functions. However, when an agency acts like a court, even though it isn’t a “full” court, it is said it is acting in a “quasi-judicial” capacity. Generally, agency quasi-judicial behavior is referred to as adjudication.

When acting in its quasi-legislative capacity, its behavior is referred to as rulemaking. The distinction between adjudication and rulemaking is important because the APA imposes different responsibilities on agencies depending on which function is performed. Rulemaking is the process whereby agencies establish law to implement or per-form a statutory duty.