Beatt K.C. (with him E. Miller), for the Commonwealth interven-
ing. (1) The Arbitration Court had jurisdiction, in exercise of
the judicial power, to determine for itself the question of the existence
of an industrial dispute. (2) If that be so, the prohibition application
must necessarily fail, because so far as the question of the existence
of an industrial dispute is concerned, the question is res judicata
for the Court. It also follows that, if this is right, for the purposes
of sec, 21a the decision of the Arbitration Court that a dispute
existed or was threatened on 19th December is a decision which binds
this Court as to whether a dispute existed on 21st December. (3)
Tn any case sec. 31 compels this Court to decide that the award
now being questioned cannot be declared void in these proceedings
even on prohibition. The effect of sec. 31 is that although the
High Court still retains its jurisdiction, it is jurisdiction in the
appropriate cases of prohibition, namely, where there has been an
excess of jurisdiction. Sec. 31 prevents parties in the Arbitration
Court who are bound by an award from challenging that award
even though it is outside the power conferred by the statute. The