In order to help to redress some of the problems of habitability experiencedin many cities, it is first imperative to establish a through knowledge of theforces which have hitherto shaped them. Many of these forces are wellknown and documented, and cities can be viewed in relation to the social, po-litical and economic factors which have exerted influence on their develop-ment. Similarly, city structure can be analyzed in termss of urban theoryor even by reference to the physical elements -materials, constructiontechniques, shapes and forms, etc. -which comprise the overall fabric.However, a factor which is rarely given serious consideration, and yet onewhich can exert a profound impact on urban development, is the instrumentof law, including both statute and common law. The former, a codified formof legislative enactment, Incorporates zoning, building regulations, ordi-nances, by laws and associated codes, and lays down specific requirementsand minima for development. While individually such laws can provide de-monstrably beneficial effects, studies indicate that the cumulative impactover time of a plethora of separate controls can have a considerable, and po-tentially detrimental, impact on the quality of the urban fabric. Common lawon the other hand, the body of recorded cases decided by civil law courts inmany western countries, collectively establishes the permlssibile actions ofgroups and individuals both working to improve the city and those living init. These too exert a considerable influence on the characteristics of the cityand its inherent livability.The purpose of this paper is to critically assess the overall impact of lawupon the city and to demonstrate its considerable influence on urban devel-opment. By reference to historical data collected from a number of citiesworldwide, it will be possible to show how legal action has helped to deter-mine urban structure (London, Paris, New York), building height and form(Chicago, Rome, Berlin) and even architectonic appearance (London, Chica-go). Case law analysis further provides the basis to assess human behaviorin regard to the city and the factors which affect the habitability of the pub-lic realm.The paper is intended as and overview of the collective influence of legalcontrols on the structure of the urban fabric. It intends to highlight the ma-jor determinants of development and establish their relative impacts, ena-bling a greater and fuller understanding of the forces which shape cities. Indoing so, it helps to establish a stronger base for those working towardschange and the improvement of the quality of life in modern urban environ-ments.