The right-wing Swiss People's Party UDC/SVP claims Switzerland is too soft on naturalisation and wants communes to decide either by panel decisions, public assembly or secret ballot without the right of appeal. The secret ballot was outlawed by the Federal Court in 2003 after considering appeals by immigrants who had been refused.

It was deemed unfair.

The cases stemmed from decisions made between 1999-2003 by voters in Emmen near Lucerne where 97 applicants, mostly from Balkan states, were refused Swiss passports although they met all the criteria.

Some communes or local authorities now use elected panels or a combination of panel and public assemblies, with the power of veto, to decide citizenship applications.

Some cantons, including Berne, Vaud and Valais, insist decisions are taken by the executive. The UDC/SVP launched an initiative to counter the Federal Court's ruling and has forced Sunday's nationwide vote on the issue.

Photograph: Getty Images / Amanda Edwards