Mandurah Enterprises Pty Ltd & Ors v Western Australian Planning Commission

Mandurah Enterprises Pty Ltd and others (the applicants) sought judicial review of a decision by the Western Australian Planning Commission (the respondent) to refuse to grant development approval for a proposed residential subdivision. The applicants contended that the Commission had failed to consider relevant matters and had taken into account irrelevant considerations when making its decision. The matter was heard by the High Court of Australia.

The central legal issue before the High Court was whether the Commission had acted unlawfully in refusing development approval. Specifically, the court was required to determine whether the Commission had properly considered the matters it was obliged to take into account under the relevant planning legislation, and whether it had excluded from its consideration matters that were irrelevant to the decision-making process. The applicants argued that the Commission had improperly focused on the potential for increased traffic congestion and the impact on existing infrastructure, which they contended were matters outside its purview at that stage of the development approval process.

The High Court found that the Commission had erred in its decision-making. The court held that the Commission had failed to give adequate weight to the planning merits of the proposal as presented by the applicants and had instead placed undue emphasis on speculative future impacts that were not sufficiently substantiated. The judges applied the principles of administrative law, particularly concerning the proper exercise of statutory discretion, emphasizing that decision-makers must consider all relevant matters and exclude irrelevant ones. The court determined that the Commission had impermissibly broadened the scope of its inquiry beyond the matters prescribed by the legislation.

The High Court allowed the appeal, quashed the decision of the Western Australian Planning Commission, and remitted the matter back to the Commission for reconsideration according to law.