Zipper system
The zipper system is a method of drawing up party lists in proportional representation electoral systems. It requires candidates on the list to alternate between men and women in order to secure equal representation in candidacy and potentially elected members.Use
Some countries mandate the zipper system in their electoral laws. It was introduced in Italy in 1993, but overturned by the constitutional court in 1995. In countries without a legal requirement, parties may choose to implement the zipper system on their own lists, such as the Swedish Social Democratic Party. The SAP's introduction of the zipper system in 1993 led to 48% of its in the 1994 general elections being female, and contributed to a record number of female MPs being elected to the Riksdag.
