Not Working

This time of year, work is the last thing on the minds of most Europeans. The E.U. mandates a minimum of four weeks holiday, guaranteeing a traditional summer exodus to beaches and mountains. When France adopted the 35-hour workweek in 2000, many employers met the requirement by simply adding to their employees' annual holiday allowances. It's not uncommon to find French workers with enough time to take both July and August off from work — paid, of course.

Yet just as summer holidays come into full swing, the 35-hour week itself looks like it might get a...