When allowed. (1) The writ shall be allowed in all cases in which a substantial interest of a plaintiff has been injured and an inferior court including an officer or tribunal other than an agency as defined in ORS 183.310 (1) in the exercise of judicial or quasi-judicial functions appears to have

(a) Exceeded its jurisdiction;

(b) Failed to follow the procedure applicable to the matter before it;

(c) Made a finding or order not supported by substantial evidence in the whole record;

(d) Improperly construed the applicable law; or

(e) Rendered a decision that is unconstitutional.

(2) The fact that the right of appeal exists is no bar to the issuance of the writ. [Amended by 1965 c.292 §1; 1973 c.561 §1; 1979 c.772 §13; 1995 c.79 §12; 1995 c.658 §29]