West v Secretary of State for Scotland 1992 SC 385 (IH) is the leading case on judicial review in Scotland and sets out in detail the present law. Unlike the position in England, the Court of Session does not require that the decision complained of should have any public law element in order to be reviewable:
… the Court of Session has power, in the exercise of its supervisory jurisdiction, to regulate the process by which decisions are taken by any person or body to whom a jurisdiction, power or authority has been delegated or entrusted by statute, agreement or any other instrument
The public or private nature of the inferior body or tribunal is not decisive, nor is it necessary to enquire whether the decision of the inferior body or tribunal is administrative in character. The essential point is that a decision-making function has been entrusted to that body or tribunal which it can be compelled by the court to perform… The essential feature of all these cases is the conferring, whether by statute or private contract, of a decision-making power or duty on a third party to whom the taking of the decision is entrusted but whose manner of decision-making may be controlled by the court.
[per Lord President Hope at page 650, emphasis added].
Crucially, in Scots law the competency of an application to the supervisory jurisdiction
… does not depend upon any distinction between public law and private law, nor is it confined to those cases which English law has accepted as amenable to judicial review...
The law of Scotland is therefore different from the law of England on this matter: see, for England, R v Chief Rabbi of the United Hebrew Congregations of Great Britain ex parte Wachmann [1992] 1 WLR 1036, in which Simon Brown J held that a decision of the Chief Rabbi to terminate a rabbi’s employment was not reviewable: to attract the court’s supervisory jurisdiction, there must be ‘not merely a public but potentially a governmental interest in the decision-making power in question.’ [at page 1046, emphasis added].