Five referendums were held in Switzerland during 1920.[1] The first three were held on 21 March on a federal law on regulating employment contracts, a ban on creating gambling establishments and a counterproposal to the ban.[1] The fourth was held on 16 May on membership the League of Nations (which Switzerland had become a founding member of the previous year), whilst the fifth was held on 31 October on a federal law on working times on railways and other transport services.[1] Of the five, only the ban on gambling establishments, League of Nations membership and the law on working times were passed.[1]
The referendum on joining the League of Nations was a mandatory referendum, whilst the ban on gambling establishments was a popular initiative.[1] Together with the counter-proposal, all three required a double majority; a majority of the popular vote and majority of the cantons.[2] The decision of each canton was based on the vote in that canton.[2] Full cantons counted as one vote, whilst half cantons counted as half.[2] The referendums on employment contracts and working times were optional referendums,[1] which required only a majority of the public vote.[2]