dissenting.
The majority affirms an order of the Energy Facility Siting Council (EFSC) that concludes that the statement of fiscal impact that accompanied the notice of intended action in the rule-making procedure for adoption of OAR 345-23-010(2) (1994) was sufficient. Because I believe that the order is insufficient for purposes of judicial review, I would reverse the order and remand this case to EFSC to make an authoritative interpretation of OAR 345-23-010(2) (1992).1 Accordingly, I dissent.
At issue in this case is the validity of OAR 345-23-010(2) (1994), which exempts certain energy facilities “for which applications have been determined to be complete under OAR 345-21-030 on or before August 13,1993,” from the requirement of demonstrating a need for power. Petitioners allege that OAR 345-23-010(2) (1994) is invalid because EFSC did not follow proper rule-making procedures in enacting the rule. Specifically, petitioners contend that the statement of fiscal impact that accompanied the rule was deficient for a number of reasons.2 Petitioners contend that one reason the fiscal impact statement is deficient is that OAR 345-23-010(2) (1994) substantially expanded the opportunity for utilities and others to build gas-fired power plants without any determination of need for power by EFSC.
EFSC rejected petitioners’ arguments challenging the sufficiency of the fiscal impact statement because, in its view, OAR 345-23-010(2) (1994) did not substantively change the law:
“In addition, the question of fiscal impact implies some change. The rule involved here has been in place essentially *162unchanged since 1992. The fiscal impact statement accompanied a proposed 1994 rule that merely limited the need exemption rule in place since 1992. The decision on the 1994 rule did not result in any material change to the fiscal impact of the rule.” EFSC’s Final Order at 7.
The majority agrees with EFSC that the fiscal impact statement for OAR, 345-23-010(2) (1994) is sufficient because that rule did not substantively change the law. To make that determination, the majority treats as controlling an interpretation of OAR 345-23-010(2) (1992) expressed for the first time by EFSC’s lawyers on review to this court.
Under the Oregon Administrative Procedures Act, this court must determine whether “the agency has erroneously interpreted a provision of law.” ORS 183.482(8)(a). Thus, this court must determine whether EFSC has “erroneously” interpreted a provision of law, namely, OAR 345-23-010(2) (1992), an administrative rule promulgated by EFSC. That issue raises important questions: In determining whether an administrative agency has “erroneously” interpreted its own administrative rule, when should the court treat an interpretation made by the agency as controlling?3 And under what circumstances should the court substitute its own judgment as to how the rule should be interpreted?
The majority appears4 to apply the following test: The court will treat an agency’s interpretation of its own administrative rule as controlling if: (1) the interpretation is not inconsistent with the express provisions of the rule, read in context; (2) the agency’s interpretation of its own rule is not inconsistent with the rule’s apparent purpose or policy; and (3) the agency’s interpretation does not place the rule in *163conflict with any other provision of law. 320 Or at 143.5 I agree with the majority that those are appropriate considerations in deciding whether the court should treat an agency’s interpretation of its own administrative rule as controlling; however, I believe that there are additional considerations that the court should consider before it treats an agency’s interpretation of its own rule as controlling.
In my view, treating an agency’s interpretation of its own rule as controlling is sometimes appropriate. When an agency has been delegated authority pursuant to statute, it is often called on to make judgments of two kinds: (1) judgments that call for “factual information and agency expertise,” and (2) judgments “about the relative importance of conflicting goals, about values and priorities, in short, policy judgments.” Marbet v. Portland Gen. Elect., 277 Or 447, 463, 561 P2d 154 (1977). Treating an agency’s interpretation as controlling is appropriate where it is the function of the agency, rather than the court, to make such judgments in the first instance. Thus, if the interpretation of an administrative rule involves the application of expertise, then treating the agency’s interpretation as controlling may be appropriate. See McPherson v. Employment Division, 285 Or 541, 549, 591 P2d 1381 (1979) (agency has “expertise” where “terms are drawn from a technical vocabulary which takes its meaning from a particular science, industry, trade, or occupation in which the agency has genuine expertise”). In addition, if the interpretation involves a determination of the agency’s policy, treating the agency’s interpretation as controlling may be appropriate because an agency is typically in a superior position to determine what it intended when it issued a rule. Davis & Pierce, Jr., 1 Administrative Law Treatise 282, § 6.10 (3d ed 1994). However, the court should not automatically treat every agency interpretation of its own rule as controlling.
Before considering treating an agency’s interpretation of its own rule as controlling, the court should make the following threshold determinations. First, the rule being *164interpreted must be a valid rule (i.e., the rule was promulgated pursuant to statutory authority delegated to the agency, is within the range of that delegation, was adopted according to proper rule-making procedure, and does not violate any statutory or constitutional provision). Second, the rule being interpreted must express agency policy, and not merely restate or interpret a statutory policy expressed by the legislature in a statute. If the rule does restate the policy embodied in a statute, then the issue is one of legislative intent, and the rule should be analyzed under Springfield Education Assn. v. School Dist., 290 Or 217, 621 P2d 547 (1980).
If the rule is valid and expresses the policy of the agency, the court should carefully consider a number of factors to determine whether it is appropriate for the court to treat the agency’s interpretation of its own rule as controlling. The majority here does identify some of those factors, namely that the agency’s interpretation is plausible in light of the text and context of the rule and other provisions of law, but fails to recognize others. In my view, the court also should consider the relative roles of the agency and the court in interpreting the rule,6 including whether the agency has the authority to make policy through adjudication.7 In addition, I believe that the court should also examine whether the agency’s interpretation is consistent with its past interpretations of the rule.8
*165Before giving an agency’s interpretation controlling weight, however, the court should consider whether the interpretation attributed to the agency is in fact an authoritative agency interpretation. Agencies may act only pursuant to statutory authority, and such authority can be exercised only by authorized personnel. The court should consider the context in which an interpretation is rendered by the agency. Thus, whether an agency’s interpretation is rendered by an individual with policy-making authority who was acting in such a capacity is an important consideration in deciding whether to treat an agency’s interpretation of its own administrative rule as controlling. Cf. Ross v. Springfield School Dist. No. 19, 300 Or 507, 516-19, 716 P2d 724 (1986) (where agency was authorized to make policy collectively, but made decisions in small panels, agency had responsibility to adopt procedure to insure consistent interpretation); see also Gage v. City of Portland, 319 Or 308, 313-17, 877 P2d 1187 (1994) (holding that no deference is owed to an interpretation of a local land use ordinance when the person interpreting the regulation is not the one who promulgated it). The context in which the asserted interpretation is made should also be considered. While it may be appropriate for the court to give controlling weight to an interpretation expressed by the agency in a contested case in which the legal issue was squarely presented, for example, it may not be appropriate to treat as controlling an interpretation made by a low-level official in some informal manner. The court should not treat as controlling an agency interpretation of its own rule that is not an authoritative statement by an authorized policy maker.
In this case, these interpretive issues are presented by OAR 345-23-010(2) (1992), which exempts certain facilities from the requirement to demonstrate need
“unless the capacity of natural gas fired facilities for which applications are pending before the Council, including the proposed facility, plus extant site certificates for natural gas fired facilities exceeds 950 megawatts at the time the application is filed.”
*166Specifically, this court must determine whether EFSC has erroneously interpreted the term “capacity,” as used in OAR 345-23-010(2) (1992).
Turning to the threshold inquiries, petitioners do not contend that OAR 345-23-010(2) (1992) is invalid. The next inquiry is whether the term “capacity,” as used in OAR 345-23-010(2) (1992), expresses the policy of the legislature or the policy of the agency. To make this determination, the court should examine the statutes which the EFSC is implementing. The exemption from the need standard in OAR 345-23-010(2) (1992) was authorized by former ORS 469.510 (1991), which provided in part:
“[T]he [EFSC] shall set standards and promulgate rules for the siting * * * of thermal plants and nuclear installations which shall take into account the following:
# H*
“(5) Present and future industrial, commercial, and residential power needs by classes and amount for each class.”
ORS 469.510 delegated to the EFSC the responsibility for adopting standards for the siting, operation, and retirement of energy facilities. With regard to the need standard and exemptions therefrom, the legislature has delegated the role of developing policy within the general state energy policies. OAR 345-23-010(2) (1992) represents a policy choice by the agency.
I next consider whether the interpretation attributed to EFSC is an authoritative agency interpretation. In my view, EFSC has not interpreted the term “capacity” in OAR 345-23-010(2) (1992), and the interpretation offered by EFSC’s lawyers on review should not be treated as controlling because that interpretation is not an authoritative agency interpretation. EFSC’s final order does not contain any reference that could be construed reasonably as an interpretation of the term “capacity,” as used in OAR 345-23-010(2) (1992), to refer to “output capacity.” See Springfield Education Assn. v. School Dist., supra, 290 Or at 227 (“under ORS 183.470, the order itself is the instrument by which an agency demonstrates that a particular interpretation or *167application of a statute is within a generally expressed legislative policy”). Nor has EFSC pointed to any other authoritative interpretation in the record.
EFSC’s lawyers on review offer arguments that, in essence, ask this court to infer that EFSC adopted such an interpretation. Arguments made in a brief during judicial review of an order such as this one, however, are not agency interpretations. EFSC can adopt only authoritative statements of law through statutorily-authorized methods. In my view, EFSC has never made an authoritative interpretation of OAR 345-23-010(2) (1992). Accordingly, this court should not treat the interpretation offered by EFSC’s lawyers on review as controlling.
In my view, the lack of an authoritative interpretation of OAR 345-23-010(2) (1992) renders EFSC’s order insufficient for purposes of judicial review. Under ORS 138.482(8)(a), this court must determine if the agency has “erroneously interpreted a provision of law.” Because the agency’s interpretation is not discernable from the order, this court cannot make that determination:
“If a statute must be interpreted to determine its applicability to the facts of a contested case, then, it is necessary for the agency to express in its order, to the degree appropriate to the magnitude or complexity of the contested case, its reasoning demonstrating the tendency of the order to advance the policy embodied in the words of the statute. Explicit reasoning will enable a court on judicial review to give an appropriate degree of credence to the agency interpretation.” Springfield Education Assn. v. School Dist., supra, 290 Or at 228.
In my view, the same need for explicit reasoning applies when an agency is interpreting its own administrative rule. There are good reasons for requiring an agency to articulate its interpretations of its own rules:
“Such articulation facilitates meaningful judicial review, enables the court on judicial review to give an appropriate degree of credence to the agency’s interpretation, serves to assure proper application of the law in the individual case, prevents judicial usurpation of administrative functions, assures more careful administrative consideration, i.e., protects against careless or arbitrary action, provides a source of *168guidance for agency personnel as well as for persons governed by the statute, helps develop and maintain the consistency in administration, facilitates the parties’ planning, i.e., helps parties plan their cases for rehearings and judicial review, and keeps agencies within their jurisdiction.” Williams v. SAIF, 310 Or 320, 329, 797 P2d 1036 (1990) (Unis, J., specially concurring; internal quotation marks and citations omitted).
In this case, EFSC’s order merely concludes that the fiscal impact statement was sufficient because the adoption of OAR 345-23-010(2) (1994) did not substantively change the law. EFSC’s order, however, does not contain any tenable basis for that conclusion. Therefore, EFSC’s order is deficient. See Ross v. Springfield School Dist. No 19, supra, 300 Or at 517 (an agency’s order “must articulate a tenable basis for the legal conclusions by which it applies a statute to the facts”).
The majority ignores the deficiency of EFSC’s order and instead gives the briefs filed in this court on review the weight of an agency’s interpretation. The majority’s seeming willingness to credit lawyers’ briefs, rather than agency orders, is troubling. This court is authorized to engage in judicial review of agency orders, not briefs, to determine if the agency has erroneously interpreted a provision of law. By accepting the post hoc rationalization for EFSC’s order articulated by EFSC’s lawyers, the majority allows the agency to perpetuate ambiguity to maximize its own authority. An agency
“cannot evade its responsibilities to interpret statutes and rules and to explain rationally why its interpretation and findings lead to its legal conclusion, even though the [agency’s] authority * * * is quite broad. Compliance by [an agency] with those responsibilities is not an act of grace.” Weems v. American International Adjustment Co., 319 Or 140, 148, 874 P2d 72 (1994) (Durham, J., concurring).
Agencies should, therefore, engage in full and careful reasoning when interpreting their own administrative rules, and they should articulate that reasoning in their orders.
Because the agency failed to articulate its interpretation of OAR 345-23-010(2) (1992), the agency’s order is insufficient for purposes of judicial review. Interpreting OAR *169345-23-010(2) (1992) requires a determination of the policy that EFSC intended to adopt with its rule. The legislature has assigned that role to EFSC in the first instance. Therefore, this case should be remanded to EFSC for further proceedings to allow EFSC to make an authoritative interpretation of OAR 345-23-010(2) (1992).
I respectfully dissent.
Fadeley, J., joins in this dissenting opinion.This case involves two versions of OAR 345-23-010(2). EFSC amended the rule in January 1994. Throughout this opinion, I refer to the original version as OAR 345-23-010(2) (1992) and to the amended version as OAR 345-23-010(2) (1994).
The statement of fiscal impact provided:
“Permanent adoption of the temporary rules is expected to have no fiscal impact on most applicants for energy facility site certificates. The proposed rules implement changes to EFSC jurisdiction as required by the new statute, clarify the requirement to show need for power for new energy facilities, and allow an exemption from the need standard for applicants whose applications were filed before August 13, 1993. The cost of preparing and reviewing applications for energy facilities site certificates is not expected to change significantly.”
I use the terminology “treat the agency’s interpretation as controlling” throughout this opinion rather than the word “deference” because the term “deference” is somewhat misleading. “Deference” implies that the court does not give an interpretation controlling weight, but rather considers the agency’s interpretation as relevant in formulating the court’s own interpretation of the rule.
I question whether this court again is failingto expressly articulate or explain the test for when the court will treat an agency’s interpretation of its own rule as controlling. See City of Klamath Falls v. Environmental Quality Comm., 318 Or 532, 538-44, 870 P2d 825 (1994) (reviewing agency interpretation of its own administrative rule under ORS 183.482(8)(a) without identifying the test for determining whether to treat an agency’s interpretation as controlling).
That test presupposes that the administrative rule itself is valid (i.e., that it was adopted in compliance with proper rule-making procedures, that it is within the scope of the agency’s authority, and that it does not conflict with any statutory or constitutional provisions).
This is a question of legislative intent that must be determined by examining the duties and responsibilities of the agency and the extent to which the legislature has expressed its policy by statute. For a similar approach regarding agency interpretations of statutes, see Springfield Education Assn. v. School Dist., 290 Or 217, 227-28, 621 P2d 547 (1980).
See Megdal v. Board of Dental Examiners, 288 Or 293, 605 P2d 273 (1980) (agency lacked authority to formulate general policy through contested cases; prior rule-making was required).
Giving controlling weight to an agency’s interpretation of its own administrative rule raises difficult questions when the agency seeks to change its policy by altering its interpretation of an administrative rule. See Weaver, Judicial Interpretation of Administrative Regulations: The Deference Rule, 45 U Pitt L Rev 587, 620-22 (1984) (discussing desirability of a requirement of consistent application). I do not mean to suggest that an agency is necessarily precluded from changing its policy through a change in interpretation, but when an agency’s interpretation has been established and relied on, a valid argument can be made that, in order to change the policy expressed by the interpretation, the agency should engage in rule-making. Cf. Gaston v. Parsons, 318 Or 247, 252, 864 P2d 1319 (1994) (a court’s interpretation of a statute is treated as if it were par t of the statute from its enactment). This case does *165not present an issue regarding the required consistency of agency interpretations of administrative rules. I read the majority’s opinion to be silent on that issue.