By merely adopting a de facto amendment to its regulation through adjudication, an administrative agency may not slip by the notice-and-comment rule-making requirements needed to amend a rule.[i]  Moreover, allowing an agency to create broad amendments to rules through administrative adjudication rather than through rulemaking undercuts the administrative procedure act of that jurisdiction.[ii]  However, the courts have also held that changes in agency rules may occur in the course of adjudication.[iii]

[i] Marseilles Land and Water Co. v. Federal Energy Regulatory Com’n., 345 F.3d 916 (D.C. Cir. 2003).

[ii] Rodriguez v. Service Lloyds Ins. Co., 997 S.W.2d 248 (Tex. 1999).

[iii] Consolidated Edison Co. of New York, Inc. v. F.E.R.C., 315 F.3d 316 (D.C. Cir. 2003).