As a part of the executive branch, agencies perform law enforcement functions. Generally, the Department of Justice, through its offices of U.S. attorneys, is responsible for enforcing criminal statutes even when the subject matter of a criminal prohibition falls within the jurisdiction of another agency. Agencies, however, prosecute the administrative aspects of such violations. While performing such functions, they exercise the same discretion that federal prosecutors do when enforcing criminal laws.

Prosecutorial discretion includes deciding whom to investigate and prosecute; whether to settle a case before, during, or after a prosecution; and related decisions. Agencies also exercise discretion to decide who shall be prosecuted. As previously mentioned, agencies do not possess the resources to prosecute every discovered violator. Although the discretion as to whom to prosecute is broad, it is still limited.

An agency that is delegated rulemaking authority has the discretion to promulgate what rules it finds necessary, and a party cannot claim that a better rule should have been promulgated. As a general rule, the courts are to defer to an agency’s interpretation of its congressional mandates. An important function performed by many administrative agencies is the processing of claims and applications.

Agencies establish practices and policies to govern the processing of these claims. Each agency has the discretion to decide its processing method. Agencies often establish testing and inspection requirements. The authority to test and inspect is extensive. Advisory opinions are a good tool for assuring compliance with the law. It is often easier to comply with requirements before engaging in a practice than it is to cease the practice later.