CAPACITY FOR GROWTH
The fourth characteristic of the system of urban law was its capacity for growth, that is, its tendency not merely to change but also consciously to develop continuously and organically.
This capacity and tendency were reflected in the occasional collection and systematization of the customs of the city or town together with the oaths of the various offices. It was also reflected in the regular enactment and periodic systematization of ordinances and laws by the governing bodies of the city or town as well as by the various guilds within it. In addition to such indigenous sources of conscious growth, urban law often benefited from the inspiration of Roman law and of the canon law. Some cities expressly "adopted" Roman law. This was always, however, the ideal, dynamic Roman law of the universities, rather than a set of unchangeable rules. Roman law was viewed as a reservoir from which legal ideas and principles could be drawn to meet new needs; hence it, too, was an element in the conscious growth of the law.