5.0 Only in defined circumstances is judicial review of a decision-making process available. To extend judicial review outside the proper boundaries of that remedy is to introduce uncertainty into the interaction of judicial and administrative power; see Efe v Minister for Justice, Equality and Law Reform  IEHC 214. There can be tribunals which of their nature deal with specialist disciplines. Where questions of the balance of policy in specialist areas, or findings of fact requiring expert assessment, are concerned, then the courts should not readily find that findings of fact are irrational or that the balance struck between competing interests fails to accord with fundamental commonsense; this is the ordinary reasonableness test but one which in respect of a specialist tribunal a court should show appropriate deference. Such specialist tribunals, however, remain obliged to stay within the jurisdiction which statute has conferred on them and are required to make their assessments on considering both sides of an issue in an appropriate way and to furnish their decisions with reasons when statute or the appropriate inference from statute so requires. Curial deference does not aid such a specialist tribunal beyond according due respect for its expert factual assessment or decision on the balance of competing interests. Curial deference cannot extend to sanctioning breaches of the rules as to jurisdiction or the bypassing of the tribunal of the obligation to incorporate fair procedures. To so regard some tribunals would be to operate a discriminatory system of judicial review.
5.2 It must be emphasised that curial deference cannot possibly arise where by statute reasons for a decision are required but none are given. Nor can curial deference ever be a factor in judicial review where a mistake of law puts a tribunal outside the jurisdiction conferred on it by statute. In appropriate cases, where errors occur even on those issues the general discretion as to judicial review may be invoked depending on the precise circumstances in appropriate cases. The principle of curial deference on issues of fact and decisions on the appropriate balancing of competing interests has, however, nothing to do with any case such as this one which concerns the obligation to give reasons for a decision and the proper interpretation of powers conferred by statute on an administrative official.Taking account of the emphasis on jurisdictional error, error of law and fair procedures, one concludes that the scope of the doctrine of curial deference in Ireland is quite limited. Deference will be accorded only on matters within a decision-maker's jurisdiction and that jurisdiction is to be determined by the courts without reference to the position taken by the decision-maker. In North America, courts are much happier to defer to decision-makers on questions of law and jurisdiction. Properly so, in my view, but it is always nice to have the opposing position illuminated.
One matter on which Irish, English and North American courts seem to agree is that reasonableness (or deference) ought to vary according to context (at least, that is what I take Charleton J. to be suggesting in his reference to "appropriate deference"). Where they seem to disagree is the scope of any doctrine of curial deference.