What is the test for standing in a civil action?

The rules and application of standing differ depending on whether one is seeking private or public interest standing, because the interests engaged differ. Vindicating private rights is the interest of the former. The latter is a matter of maintaining the rule of law as a general principle, regardless of whether a private right or interest is involved. As Chief Justice Laskin, speaking for the majority, said in Thorson v. Attorney General of Canada, 1974 CanLII 6 (SCC), [1975] 1 S.C.R. 138, at p. 145: [ . . . ] it would be strange and, indeed, alarming, if there was no way in which a question of alleged excess of legislative power, a matter traditionally within the scope of the judicial process, could be made the subject of adjudication.