The failure of a public authority to take into account relevant considerations and the taking of irrelevant ones into account are grounds of in Singapore administrative law. They are regarded as forms of illegality. If, in the exercise of its discretion on a public duty, an authority takes into account considerations which the courts consider not to be proper, then in the eyes of the law it has not exercised its discretion legally. On the other hand, considerations that are relevant to a public authority's decision are of two kinds: there are mandatory relevant considerations (that is, considerations that the statute empowering the authority expressly or impliedly identifies as those that must be taken into account), and discretionary relevant considerations (those which the authority may take into account if it regards them as appropriate). If a decision-maker has determined that a particular consideration is relevant to its decision, it is entitled to attribute to it whatever weight it thinks fit, and the courts will not interfere unless it has acted in a Wednesbury-unreasonable manner. This is consistent with the principle that the courts are generally only concerned with the legality of decisions and not their merits. In the United Kingdom, it has been suggested that if the court interprets a statute to impose a duty on a public authority, the resources available to the authority are irrelevant to deciding how the duty should be carried out. Conversely, if the court interprets a statute to confer a discretionary power on a public authority, then resources are a relevant consideration. Also, public authorities are not required to take into account people's fundamental rights arising under the Human Rights Act 1998 as relevant considerations before arriving at decisions. Their only responsibility is to ensure that the decision itself complies with the European Convention on Human Rights. At present, there are no Singapore cases on these issues. (en)