The Town Planning Board is appealing against a court judgment that could have far-reaching implications for the city's rules to limit the height of buildings. In May, the Court of First Instance questioned the basis for planning restrictions affecting the redevelopment of four blocks at Kai Tak Mansion in Kowloon Bay into a single 45-storey, 203-metre high block of flats. The restrictions imposed include a height limit of 130 metres, the designation of areas which may not be built on and a requirement to leave a 20-metre wide gap in the centre of the site. The height cap was less than 65 per cent of the tower's proposed height. The developer, Oriental Generation, wanted the height limit raised to 140 metres. The court quashed the restrictions, calling them arbitrary. It requested the board reconsider whether any restrictions should be imposed on the site. The Planning Department said the board had decided to appeal, and a hearing was scheduled for May next year. The board has also applied to the High Court for a stay of execution of the judgment. The case is considered to have wider implications for urban planning, as the department has been introducing controls, including height limits, in various districts since 2007. The outcome of the appeal hearing could trigger legal challenges from other developers whose interests have been undermined by such rules. The department could also face difficulties if it seeks to continue imposing controls in other districts. In June, the Real Estate Developers Association urged the board to review the planning controls to be imposed in Kwai Chung district, given the case of Kai Tak Mansion. "The Town Planning Board has no choice but to appeal," said a board member, who declined to be named. "The impact is inconceivable. If the [town planning] board loses the appeal, it may have to take it to the Final Court Appeal." The member said legal consultants put the board's chances of winning the battle as slim. "Instead of making appeals, it is urgent for the government and the board to improve its mechanism of imposing planning controls in the long run," the member said. Institute of Urban Design vice-president Vincent Ng Wing-shun said the government needed to convince the public and site owners that its planning rules had a scientific basis. He said even professionals did not know how officials came up with specific height limits. "They need to give clear justifications and exhibit models for the public to understand the rationale for controls," Ng said. In the case of Kai Tak Mansion, the reason given was to prevent any new structure restricting views of the former Royal Air Force quarters, a historic site behind the apartments.