custom and tradition 

(n.) What has been done for a very long time, although rarely recorded. Custom and tradition can often over-rule statute law.

An example of custom and tradition is leaving newspapers outside a newsagents' in the early morning, allowing them to be taken by passers by. The delivery company does not have to change its' ways legally because ti falls under custom and tradition, and this practice dates back to the first instances of newspapers in the western world.

custom and tradition by Gumba Gumba June 3, 2004