(1) Any person whose interest may be substantially affected by a proceeding before the board may by motion request status as an amicus in the case. The motion must comply with WAC 456-10-510 and 456-10-410.

(2) The motion requesting amicus status must include a statement of the following:

(a) Applicant's interest, or the interest of the person or group represented by applicant, in the proceeding before the board;

(b) Applicant's familiarity with the issues involved in the proceeding before the board and with the scope of the arguments presented or to be presented by the parties;

(c) Specific issues to which the amicus curiae brief will be directed; and

(d) Applicant's reason for believing that additional argument is necessary on these specific issues.

(3) The brief of amicus curiae may be filed with the motion but must be filed no later than the time set for the filing of the brief for the party whose position the amicus supports.

(4) The board, on its own motion and with notice to the parties, may request a brief of amicus curiae from any person deemed to be substantially affected by a proceeding before the board.