Hong Kong is the most densely populated city in the world. Design of buildings in urban Hong Kong is regulated by the Building (Planning) regulations of the Government. This piece of law is over 40 years old and has been proven to be inadequate. This paper introduces a new simplified method, the Unobstructed Vision Area Method (UVA), for daylight design in high-density cities. The method was developed based on empirical and theoretical formulation as well as extensive validation and studies using computational simulations. The paper highlights the steps necessary to apply computational methods for law making, the difficulties and possibilities in the process, as well as the practical and implementation of adopting computational results and techniques in everyday practical life of the architect and the controlling agency. The Government of Hong Kong has recently adopted the UVA method.