531 (Chinese: 保護海港條例) is an ordinance in Hong Kong Law that aims to limit land reclamation in the surviving waters of Victoria Harbour.

[3] The Government proposed the Central and Wan Chai Reclamation project in the 1980s, long before the inception of the ordinance.

[4] However, when the Government later planned to start the remaining phases of the reclamation, conservationists saw the ordinance as a means to stop the projects.

The Society for Protection of the Harbour applied for a stay of order and judicial review on September 25, 2003, prohibiting the government from continuing the third phase of the Central reclamation project.

On 1 September 2004, the Court of Final Appeal rejected the Town Planning Board's proposal on the draft Wan Chai North Outline Zoning Plan (OZP); further, the Wan Chai Development Phase 2 had to be reviewed.