Switzerland is a democratic federal republic. The federal legislative power is vested in the two chambers of the Federal Assembly, the National Council and the Council of States. The Federal Council holds the executive power and is composed by seven power-sharing Federal Councillors elected by the Federal Assembly. The judiciary branch is represented by the Federal Supreme Court of Switzerland, whose judges are elected by the Federal Assembly.
The citizens can challenge any law passed by the Parliament if they can gather 50,000 signatures against the law within 100 days.
Source: https://en.wikipedia.org/wiki/Politics_of_Switzerland, http://www.expatica.com/ch/about/35-facts-about-Switzerland_100041.html