(1) In addition to other rule-making requirements imposed by law:
(a) Each agency may adopt rules governing the formal and informal procedures prescribed or authorized by this chapter and rules of practice before the agency, together with forms and instructions. If an agency has not adopted procedural rules under this section, the model rules adopted by the chief administrative law judge under RCW
34.05.250 govern procedures before the agency.
(b) To assist interested persons dealing with it, each agency shall adopt as a rule a description of its organization, stating the general course and method of its operations and the methods whereby the public may obtain information and make submissions or requests. No person may be required to comply with agency procedure not adopted as a rule as herein required.
(2) To the extent not prohibited by federal law or regulation, nor prohibited for reasons of confidentiality by state law, each agency shall keep on file for public inspection all final orders, decisions, and opinions in adjudicative proceedings, interpretive statements, policy statements, and any digest or index to those orders, decisions, opinions, or statements prepared by or for the agency.
(3) No agency order, decision, or opinion is valid or effective against any person, nor may it be invoked by the agency for any purpose, unless it is available for public inspection. This subsection is not applicable in favor of any person who has actual knowledge of the order, decision, or opinion. The agency has the burden of proving that knowledge, but may meet that burden by proving that the person has been properly served with a copy of the order.
(4) Each agency that is authorized by law to exercise discretion in deciding individual cases is encouraged to formalize the general principles that may evolve from these decisions by adopting the principles as rules that the agency will follow until they are amended or repealed.
(5) To the extent practicable, any rule proposed or adopted by an agency should be clearly and simply stated, so that it can be understood by those required to comply.
(6) The departments of employment security, labor and industries, ecology, and revenue shall develop and use a notification process to communicate information to the public regarding the postadoption notice required by RCW
34.05.362.