PARIS, France (CNN) -- The French Senate began debate Tuesday on a law that would mark a significant cultural shift -- allowing many more shops across the country to open on Sundays.
The law would permit shops, department stores, and shopping malls to open on Sundays in 20 zones.
The bill passed the lower house, the National Assembly, last Tuesday by a vote of 282 to 238, a partial victory for President Nicolas Sarkozy, who backs it.
What seems routine in much of the Western world has been fiercely resisted in France, where Sundays have officially been set aside as a day of rest for more than a century and where a 35-hour workweek remains the norm.
The new legislation, if approved by the Senate, would overturn a 1906 law that forbids Sunday trading in all but the largest cities. It is part of a raft of reforms Sarkozy has pushed for since becoming president.
While the change is significant, it is not as much as the government originally hoped because Sarkozy had to deal with opposition from both the left and the right.
Socialists filed thousands of amendments to the president's original version of the law. Leftists and unions said it would effectively introduce a seven-day working week and allow bosses to force employees to work Sundays.
Members of the president's own ruling conservative party opposed the law despite assurances it would boost economic activity, saying it would instead deprive families and church groups of their dedicated day.
The law would permit shops, department stores and shopping malls to open on Sundays in 20 zones of what are called "exceptional commercial" centers near three of the country's largest cities: Paris, Marseilles, and Lille.
Additionally, 29 areas involving about 500 cities and towns would be added to the list of tourist areas, which already allow some economic activity on Sundays.
The new law will, among other things, straighten out a somewhat chaotic situation in which some stores managed to obtain exceptions from the old law and others didn't, and where some stores found it made more sense financially to accept fines for breaking the old law because the income from Sunday sales more than made up for the penalties.
Opinion polls in France show that slightly more than half the population want shops to have the freedom to open on Sundays, according to Time magazine.
The Senate debate is scheduled to last three days, with a vote expected late on Thursday.
CNN's Jim Bittermann contributed to this report.