Western Australian Planning Commission v. Southregal Pty Ltd & Anor; Western Australian Planning Commission v. Leith

The High Court of Australia considered appeals from the Supreme Court of Western Australia concerning the validity of certain planning approvals granted by the Western Australian Planning Commission (WAPC). The primary parties were the WAPC, Southregal Pty Ltd, and Leith. The dispute centred on whether the WAPC had acted lawfully in granting development approval for a residential subdivision and associated infrastructure, specifically addressing whether the WAPC had failed to properly consider the environmental impact of the proposed development, particularly concerning the habitat of the Western Ringtail Possum.

The central legal issues before the High Court were whether the WAPC had breached its duty to consider relevant matters under the *Environmental Protection Act 1986* (WA) and the *Planning and Development Act 2005* (WA) by failing to adequately assess the environmental impact on the Western Ringtail Possum, and whether the WAPC had failed to provide adequate reasons for its decision. The court also had to determine if the Supreme Court of Western Australia had erred in finding that the WAPC's decision was invalid due to these alleged failures.

The High Court held that the WAPC had not acted unlawfully. Their Honours found that the WAPC had considered the relevant environmental factors, including the impact on the Western Ringtail Possum, and had provided sufficient reasons for its decision. The court emphasised that the WAPC's duty was to consider relevant matters, not to conduct an exhaustive environmental impact assessment itself, which was the role of the Environmental Protection Authority. The court concluded that the WAPC had taken into account the information available to it and had made a decision that was open to it under the relevant legislation.

Consequently, the High Court allowed the appeals, setting aside the orders of the Supreme Court of Western Australia and upholding the validity of the planning approvals granted by the WAPC.