Reply #17: per the Washington State Constitution

[onenote]

The AG is "the legal adviser of the state officers, and shall perform such other duties as may be prescribed by law."

By statute, the legislature has assigned various duties to the AG, including

General powers and duties.

The attorney general shall:

(1) Appear for and represent the state before the supreme court or the court of appeals in all cases in which the state is interested;

(2) Institute and prosecute all actions and proceedings for, or for the use of the state, which may be necessary in the execution of the duties of any state officer;

....
(5) Consult with and advise the governor, members of the legislature, and other state officers, and when requested, give written opinions upon all constitutional or legal questions relating to the duties of such officers;

....
(7) Give written opinions, when requested by either branch of the legislature, or any committee thereof, upon constitutional or legal questions;

The wording of these assignments of duties is murky enough to leave the question you raise about the duties and role of the AG somewhat unclear. Arguably, none of the enumerated duties covers his bringing the suit.