Union strategy and optimal income taxation

"Restrictions on work hours are more important in countries with a large welfare state. We show that this empirical observation is consistent with the strategic effects of such restrictions in a welfare state in the context of optimal direct taxation in the tradition of Mirrlees (1971). Our results also apply to non-welfarist states which have income redistribution, but not in purely extortionary states"--Forschungsinstitut zur Zukunft der Arbeit web site.