An administrative decision-maker under a duty to give reasons commits an error of law if it fails to give adequate reasons; however, when deficiencies in reasons manifest a failure to comply with a specific statutory obligation (as with s 170CG(3)(a)), this constitutes a jurisdictional error regardless of the general duty to give reasons.

An administrative tribunal established by statute lacks authority to determine questions of law otherwise than in accordance with the law; any misdirection in law which causes the tribunal to identify a wrong issue, ask itself a wrong question, or ignore relevant material constitutes jurisdictional error that will invalidate the tribunal's decision.

The principles applicable to reviewing a discretionary decision made by an inferior court or administrative tribunal; error must be shown to affect the tribunal's exercise of power.

An exercise of discretion may be found to be erroneous where the decision-maker acted on a wrong principle, took into account irrelevant matters, mistook facts, or is manifestly wrong.

A distinction remains in Australian law between jurisdictional error and error within jurisdiction; an error in the exercise of discretion committed to a tribunal is error within jurisdiction, not jurisdictional error.

In statutory interpretation, the task is to ascertain the intention of the legislature as manifested by the text; context and the purpose or object underlying the legislation must always be considered; the text of a provision, read in context and having regard to the object and purpose, is the surest guide.

An appeal under s 90(1)(b) will succeed where the Full Bench has made an error in the interpretation of the Act that affects its jurisdiction to grant relief, such as wrongly assuming it has no jurisdiction to award damages in relation to a contractual benefit claim.

The common law in Australia must evolve within the limits of judicial power and not trespass into the province of legislative action. The exercise of law-making function can only occur as an incident of adjudication of particular disputes, with reference to the web of established legal principle.

The Public Service Arbitrator does not possess independent power to engage in 'judicial review' or to make bare declarations of illegality; however, in determining how to deal with an industrial matter, the Arbitrator may make factual findings suggesting unlawful conduct as a step in dealing with the industrial matter.

For an administrative tribunal, jurisdictional error occurs where an error of law causes it to identify a wrong issue, ask a wrong question, ignore relevant material, rely on irrelevant material, or reach a mistaken conclusion, and that error affects the tribunal's exercise or purported exercise of power.

An appeal cannot be made on the ground of error in construction or interpretation of the Act where the Full Bench has merely applied law which it has correctly understood to the facts of an individual case. It is for the Full Bench to weigh the relevant facts in light of the applicable law.

An appellate court will not order a new trial if it would inevitably result in the making of the same order as the primary judge, as such an order would be a futility.