(2) The relator shall serve a copy of the petition on the defendant and, if the mandamus proceeding arises from a judicial or administrative proceeding, on all parties to such proceeding. Service of the petition on the defendant and adverse parties is sufficient if it complies with ORCP 9 B. The court in its discretion may act on a petition regardless of defects in the service of the petition on any adverse party, and the petition may be allowed with or without notice to the adverse party, as in a writ of review proceeding.

(3) Except as to a petition filed in the Supreme Court, the writ shall be allowed by the court or judge thereof on the petition. On the filing of the order of allowance, the clerk or court administrator forthwith shall issue the writ in accordance with the petition. The clerk or court administrator may require the relator to provide a form of writ in accordance with the petition.

(4)(a) Except as provided in paragraph (b) of this subsection, at any time in the course of a mandamus action until the return date of the alternative writ, any adverse party may intervene in the mandamus proceeding as matter of right. At any time subsequent to the return date of the alternative writ, the court in its discretion may allow an adverse party to intervene. With the consent of the defendant and, if the defendant is a judge of the Supreme Court, Court of Appeals, Oregon Tax Court or circuit court, subject to ORS 1.550 and 1.560, the attorney for an adverse party may appear on behalf of the defendant.

(b) For a petition filed pursuant to ORS 215.429 or 227.179, a motion to intervene must be filed with the court within 21 days of the date the petition was filed under subsection (1) of this section.

(5) The filing or allowance of a petition for a writ of mandamus does not stay any judicial or administrative proceeding from which the mandamus proceeding may arise, but the court in its discretion may stay such proceeding. [Amended by 1971 c.193 §27; 1989 c.702 §3; 1999 c.533 §2]