The French have a special knack in messing with labor markets. The last spectacular failure was the law that limited almost everyone's workweek to 35 hours in the hope this would spread the total hours to more people, lead to more employment and solve a chronic unemployment problem. Well, it did not and lead to loss of productivity and ridiculed controls. And I doubt many economists were surprised. With the election of Sarkozy, this law was quickly scraped and an equally ridiculous law from the other end of the spectrum was introduced.
Pierre Cahuc and Stéphane Carcillo discuss the French policy of making overtime work tax exempt. One can really question what Sarkozy had in mind with this policy, as the adverse consequences are all too obvious. First what is overtime is easily manipulated, and suddenly many regular hours became overtime hours. Second, if the intend was to increase the total hours of work, it was bound to fail if most of the overtime is coming from workalcoholics who would work no matter what the wage is. This is why you need to tax them instead of subsidizing them. And Cahuc and Carcillo find that indeed total hours hardly changed. So what all this amounted to is a generous lump-sum subsidy to highly-skilled workalcoholics. Great.