Optional referendum

[1] The ratification of the Gotthard Treaty of 1909 triggered widespread protests and ultimately led to a petition being submitted.

The number of signatures required from Swiss voters for a popular referendum was initially 30,000.

Due to the massive increase in the number of voters due to population growth and the introduction of women's suffrage in 1971, the number was increased to 50,000 valid signatures in 1977.

It related to changes in marriage, family and housing taxation (the so-called “tax package”).

[2] On a federal level a vote will be organised on every law against which opponent collect 50,000 valid signatures during the period of 100 days after publication by the parliament.