Illegality in Singapore administrative law

Illegality is one of the three broad headings of judicial review of administrative action in Singapore, the others being irrationality and procedural impropriety. To avoid acting illegally, an administrative body or public authority must correctly understand the law regulating its power to act and to make decisions, and give effect to it.

The broad heading of illegality may be divided into two sub-headings. In the first case, the High Court inquires into whether the public authority was empowered to take a particular course of action or make a decision, and, in the other, whether it exercised its discretion wrongly even though it was empowered to act. Where the Court finds that the public authority had exceeded its jurisdiction or had exercised its discretion wrongly, it may invalidate the act or decision.

Under the first sub-heading, a public authority will be considered as having acted illegally if there is no legal basis for the action carried out or the decision made (simple ultra vires), or, more specifically, if the authority has made an error concerning a jurisdictional or precedent fact. A precedent fact error is made when an authority comes to a conclusion in the absence of facts that must objectively exist, or in the presence of facts that must not exist, before it has the power to act or decide.

In cases falling under the second sub-heading, a public authority has satisfied all the factual and legal conditions required for exercising a statutory power conferred upon it, but nevertheless may have acted illegally by doing so in a manner contrary to administrative law rules. The grounds of review available under this heading include the authority acting in bad faith, acting on the basis of no evidence or insufficient evidence, making an error of material fact, failing to take into account relevant considerations or taking into account irrelevant ones, acting for an improper purpose, fettering one's discretion, and not fulfilling a person's substantive legitimate expectations.