Under the Swiss Federal Constitution, the mode of election to the Council of States is left to the cantons, the provision being that it must be a democratic method. All cantons now provide for the councillors to be chosen by popular election, although historically it was typically the cantons' legislatures that elected representatives to Bern. However, eligibility to vote varies according to the applicable cantonal law. One notable variation is that qualified foreigners may vote in Neuchâtel and Jura, and the minimum voting age is 16 in Glarus. In all the cantons except canton of Appenzell Innerrhoden the councillors are elected concurrently with the members of the National Council. In Appenzell Innerrhoden the representative is elected by the popular assembly during the April before the national vote. With the exception of the cantons of Canton of Neuchâtel and Canton of Jura, which have proportional representation, councilors of state are elected by majority vote in either one or two rounds of voting.
Working languages
In debates, councilors can choose any of the federal languages, usually the one they are most proficient in: German, French, Italian, or Romansh. German and French are the most frequently used.
'''Seats by party at the Council of States of Switzerland !style="background-color:#E9E9E9;text-align:left;" colspan=2| Parties !style="background-color:#E9E9E9;text-align:left;" | Ideology !style="background-color:#E9E9E9;text-align:right;"| 2003 !style="background-color:#E9E9E9;text-align:right;"| 2007 !style="background-color:#E9E9E9;text-align:right;"| 2011 !style="background-color:#E9E9E9;text-align:right;"| 2015 !style="background-color:#E9E9E9;text-align:right;"| 2019
Population per seat
The Council of States represents the federal nature of Switzerland: seats are distributed by state, not by population. Most cantons send 2 representatives, while the historic half-cantons; Appenzell Ausserrhoden, Appenzell Innerrhoden, Obwalden, Nidwalden, Basel-Stadt and Basel-Landshaft, each send one. Consequently, the number of people represented by a single seat in the Council of State varies by a factor of 45.8, from 15,000 for the half-canton of Appenzell Innerrhoden to 733,050 for each of the two seats for the canton of Zurich. Notes: ¹ Population data from 2015. ² Relative representation compared to Zürich.