A right to address the Court on a matter before it.
In 604598 Saskatchewan Ltd. v Sask. Liquor and Gaming Authority 157 DLR 4th 82 (1998), and published at canlii.org/en/sk/skca/doc/1998/1998canlii12308/1998canlii12308.html, the Saskatchewan Court of Appeal adopted these words in regards to locus standi:
"A place of standing; standing in court. A right of appearance in a court of justice ... on a given question.
"Roughly speaking, this place of standing, enabling a person to appear before and be heard by a court in relation to a given question, may be acquired in one of two ways: as of right, in reliance upon one's own private interests in the question (private interest standing); or with leave of the court in reliance largely upon the public's interest in the question (public interest standing).
"And standing may exist, or be granted, in both civil and criminal proceedings, proceedings of one sort or another involving claims of various kinds, including a claim that a law is unconstitutional."