"That power is a discretionary one in the sense that its
exercise involves a subjective balancing process in which the
relevant factors will vary and in which both the question of the
comparative weight to be given to particular factors in the
circumstances of a particular case and the decision whether the
power should be exercised are matters for individual judgment
and, to a significant extent, matters of impression. The power
should only be exercised in a clear case and the onus lies upon
the defendant to satisfy the local court in which the particular
proceedings have been instituted that it is so inappropriate a
forum for their determination that their continuation will be
oppressive and vexatious to him. Ordinarily, a defendant will be
unable to discharge that onus unless he can identify some
appropriate foreign tribunal to whose jurisdiction the defendant
is amenable and which would entertain the particular proceedings
at the suit of the plaintiff. Otherwise, that onus will
ordinarily be discharged by a defendant who applies promptly for
a stay or dismissal if he persuades the local court that, having
regard to the circumstances of the particular case and the
availability of the foreign tribunal, it is a clearly
inappropriate forum for the determination of the dispute between
the parties. The reason why that is so is that, once it is
accepted that the adjectives "oppressive" and "vexatious" are
not to be narrowly or rigidly construed and are to be applied in
relation to the effect of the continuation of the proceedings
rather than the conduct of the plaintiff in continuing them, the
continuation of proceedings in a tribunal which is a clearly
inappropriate forum would, in the absence of exceptional
circumstances being established by the plaintiff ... be
oppressive or vexatious to such a defendant ..."