Sec. 44.62.240. - Limitation on retroactive action.
If a regulation adopted by an agency under this chapter is primarily legislative, the regulation has prospective effect only. A regulation adopted under this chapter that is primarily an "interpretative regulation" has retroactive effect only if the agency adopting it has adopted no earlier inconsistent regulation and has followed no earlier course of conduct inconsistent with the regulation. Silence or failure to follow any course of conduct is considered earlier inconsistent conduct.