To prevent a concentration of power Switzerland has three independent powers: the legislative power, the executive power and the judiciary power. In Canton Aargau the following authorities exercise these powers:
- Legislative power: Grand Council (Grosser Rat) (140 members, elected by the public every four years)
- Executive power: Cantonal Government (Regierungsrat) (5 members, elected by the public every four years)
- Judiciary power: Various courts on the levels of the districts and the canton
The communities also have a legislative power (community assembly or parliament) (Gemeindeversammlung, Parlament) and an executive power (city council or community council) (Stadtrat, Gemeinderat). The national government (7 members) is called the Federal Council (Bundesrat). On the national level there are various courts. The Federal Tribunal is the highest instance where, for example, cantonal rulings can be appealed against.