(1) Petition. Any interested person may petition the commission for a declaratory order with respect to the applicability to specified circumstances of a rule, order, or statute enforceable by the commission, as provided by RCW 34.05.240.

(a) Format. Petitions for declaratory orders under RCW 34.05.240 must conform in style and substance to the requirements for other forms of adjudicative pleading as specified in Part III, subpart A of this chapter.

(b) Relationship with adjudications. The commission will dismiss a petition for declaratory order when issues in the petition are at issue in a pending adjudication. The commission will reject a single pleading that purports to present the commission with the option to enter either a declaratory order or an adjudicative order. The filing party must specify a single process under which it requests that the commission proceed.

(2) Notice. The commission will give notice of any petition for declaratory order within fifteen days after the commission receives the petition. The commission will serve notice on all persons who are required by law to be given notice and on any other person to whom the commission deems notice to be desirable.

(3) Response. Any person may respond to a petition for declaratory order by filing a response within twenty days after the petition is filed or at such other time as the commission may establish by notice. The commission will not enter a declaratory order under RCW 34.05.240 if any person:

(a) Asserts in response to a petition for declaratory order filed pursuant to RCW 34.05.240 that their rights might be substantially prejudiced by entry of a declaratory order;

(b) Supports such assertion by sworn statement in the form of a declaration or affidavit demonstrating the potential for substantial prejudice; and

(c) Does not consent in writing to the determination of the matter by a declaratory order proceeding under RCW 34.05.240.

(4) Conversion of proceeding. The commission may convert the form of a declaratory order proceeding as provided under RCW 34.05.070 and conduct the matter as an adjudicative proceeding under Part III, subpart A of this chapter.

(5) Commission action on petition. Within thirty days after it receives a petition for declaratory order, the commission will:

(a) Enter a declaratory order;

(b) Notify the petitioner that the commission will not enter a declaratory order under RCW 34.05.240 and state the reasons for that decision;

(c) Set a specified time, no later than ninety days after the day the petition was filed, by which the commission will enter a declaratory order; or

(d) Set a reasonable time and place for a hearing. The commission will hold any hearing on a petition for declaratory order under RCW 34.05.240 within ninety days after receipt of the petition. The commission will give at least seven days' notice of any hearing to the petitioner, to all persons to whom notice is required by law, and to any other person the commission deems desirable. The notice will include the time and place for the hearing and a statement of the issues the commission will consider.

(6) Extension of time. The commission may extend the times specified in subsection (5)(c) and (d) of this section for good cause.

(7) Commission action after hearing. The commission will take one of the following actions within a reasonable time after holding any hearing as provided in subsection (5)(d) of this section:

(a) Enter a declaratory order; or

(b) Notify the petitioner that the commission will not enter a declaratory order and state the reasons for that decision.