State law establishes the law as far as cities and towns are concerned.
The most obvious of which is the legislative body that is either the city council or the town board. The elected members of the city council or town board have the final say on land use matters except for those designated to the board of adjustment. The planning commission is an advisory board to the city council. The number of members and length of terms is set by each municipal ordinance. The state law does require that they meet at least once a month.