In Ohio, USA:
rural areas governemt are called statutory governemnt becase the rules are written into the sate's statues (laws, Ohio Revised Code). Once an area's population is large enough they can opt for to a village or city government.
Then they can chose to write their own constitution and this means thye are no longer covered by the rules of the statues.
For example, a city may say that a open seat in council is filled by a chose of the mayor or the choice of the council; under ORC the rules say a speical election is held. (this is sometimes called home-rule or home-charter)