A two-part referendum was held in Switzerland on 23 May 1875.^[1] A new federal law establishing and certifying civil status and marriage was narrowly approved, whilst a new federal law on suffrage was narrowly rejected.^[1]

This was the first optional referendum held in the country, as all previous referendums had been mandatory referendums.^[2] Whilst obligatory referendums required both a majority of voters and a majority of cantons in favour, optional referendums required only a majority of the public vote.^[3]