The federal law, which is due to be discussed in parliament on February 29th, aims to harmonize shop opening hours across the country with proposed times of 6am-8pm Monday-Friday and 6am-7pm on Saturdays.
At the moment opening hours are set at cantonal and communal level, meaning that while the new law would have no effect in cantons that already allow shops to stay open until 8pm, such as Zurich, employees in 14 cantons including Vaud, Valais and Lucerne could see their working hours considerably extended.
In Unia's poll, 96 percent of the 2,520 people surveyed were opposed to the law, while just 1.85 percent were in favour and 2.1 percent had no opinion.
There was no significant difference in opinion across the country, said Unia.
“The prospect of having to work later into the evening is clearly rejected by those surveyed,” it said in a statement.
“The results are more marked than in previous surveys, probably because employees feel the threat more and more,” it added.
However many retailers are in favour of the new law, expressing frustration at current limits to store openings in many parts of Switzerland, particularly in cantons bordering neighbouring countries where opening hours are longer.
Backing the changes, Swiss commerce group CICDS says longer opening hours are necessary to meet changing consumer habits.
“The flexibility of working hours, longer commutes and the evolution of family life means an increasing number of Swiss are doing their shopping in the evening,” said CICDS in a statement on its website.
“Swiss traders are not asking to open their shops 24 hours a day,” it added. “They are looking for ways to offer an appropriate response to changing shopping and leisure habits in Switzerland.”
However SGB, an umbrella organization for trade unions, disagrees.
Writing on the organization's website earlier this week, Luca Cirgliano, a member of the SGB's secretariat, said the new law smacked of a “salami strategy” to implement 24/7 opening by degrees.
“Supporters of total deregulation prefer to proceed by small steps, hoping that the electorate will not see what they're doing,” he said.
“Each small step in the direction of deregulated hours... serves the final objective of extending opening hours of all shops and stopping or limiting the ban on evening and Sunday work.”
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He also slammed the new law's “clear threat to working conditions”.
Currently, jobs which require employees to work evenings or on-call “are the cause of an increase in stress and cases of ‘burnout', as well as being a threat to work-life balance,” said Cirgliano.
“The new law on shop opening hours would worsen working conditions for more than 200,000 workers.”
If the new law is accepted by parliament Unia said it would push for a referendum on the matter.