Issues of sub-national referendums regulated at the national level

Constitution

http://www.constitution.ru/en/10003000-01.htm

Article 131

1. Local self-government shall be administered in urban and ruralsettlements and in other areas with the consideration of the historical andother local traditions. The structure of local self-government bodies shall bedetermined by the population independently.

2. Changes in borders of the areas in which local self-government isadministered shall be made with the consideration of the opinion of thepopulation of the corresponding areas.