Foreigners have less chance of obtaining a Swiss passport if voters decide on citizenship applications at the ballot box, according to a study.
Experts also found that the presence of the rightwing Swiss People’s Party in local politics has an impact on citizenship votes.
The report comes after controversy over some of the methods used by communes to decide whether or not to grant a Swiss passport.
In Switzerland the citizenship process is based on approval by the federal, cantonal and local authorities, which set their own rules and fees.
Communes use a range of procedures, such as public assemblies and panel assessments, to decide. Until recently secret ballots were also allowed.
The Swiss National Science Foundation study, which was released on Tuesday, found that in villages and towns where citizenship applications were put to a secret popular vote, the refusal rate was 23 per cent higher than for other procedures.
"We were expecting that the procedure used to decide naturalisation would influence the result," said co-author Marc Helbling from Zurich University.
"But that a ballot box decision increased the chances of a refusal by almost one quarter was a big surprise," he said.
The authors, who examined data from 207 communes, said that they were also surprised that the public assemblies procedure, which normally entails a show of hands, was not more restrictive.
"This is explained by the fact that xenophobic arguments have a greater repercussion on anonymous votes than on other procedures such as a naturalisation panel," said the authors.
The report downplayed the influence of factors which were thought to be important, such as the local unemployment rate and the number of foreigners living in the area.
More decisive, said the authors, was how active the rightwing Swiss People’s Party was in local politics.
They found that where influence was high, the success rate for citizenship dropped by five per cent. However, the left-leaning parties, usually more foreigner-friendly, appear to have no influence at all.
Another factor is how the Swiss identity is viewed and how restrictive these perceptions are. Communes have the final say in the complex naturalisation procedure in Switzerland.
In 2003 the Federal Court outlawed popular votes on citizenship requests and later ruled to ban secret ballots by commune assemblies.
The decisions came after voters in the town of Emmen near Lucerne turned down 97 applications from foreigners, mostly from the Balkans. Similar votes in other communes in central Switzerland caused a public outcry.
But the People’s Party is hoping to challenge the court ruling in a nationwide vote.
Last September, Swiss voters rejected parliament-backed proposals to make it easier for young foreigners to become citizens.
It was the second time in a decade that voters refused to ease citizenship rules. Foreigners currently number 1.5 million – about 20 per cent of the population.
The application process for Swiss citizenship is usually long and complicated. The procedure is in some cases also expensive – although this should change next year - without guarantees that the application will be successful.
As a result, Switzerland has one of the lowest levels of naturalisation in Europe.
swissinfo with agencies
In communes using secret ballots, the refusal rate for citizenship requests rose by 23%.
In communes with a strong rightwing Swiss People’s Party presence, refusals were up by 5%.
A restrictive view of what it meant to be Swiss led to 4% more refusals.
Parties to the Left did not seem to influence citizenship procedures.
The study comes at a time of heightened discussion over the citizenship procure in Switzerland. In 2004 voters rejected a proposal to ease the naturalisation process for second-generation foreigners.
The right of the community to have a last say in the process is unique in Europe. Methods include votes by local assemblies and parliaments and panel assessment.
In 2003 the Federal Court said that secret community ballots were illegal because they were not transparent. But the rightwing Swiss People’s Party is campaigning to reintroduce this.