I want to know the answer to the following question:
What can citizens use to challenge any law passed by Parliament?
All the background I'm provided with is that "The Swiss Parliament consists of two houses: the Council of States which has 46 representatives (two from each canton and one from each half-canton) who are elected under a system determined by each canton, and the National Council, which consists of 200 members who are elected under a system of proportional representation, depending on the population of each canton.". Is that enough to answer the question?
Answer: no