The relationship between trade unionism and politics has been a very traditional issue since the industrial revolution and the development of democratic societies. We propose to examine it from a new perspective. It is no longer a question of decoding the links between trade unionism and ideologies or political parties. Nor is it a question of differentiation between professional and political action. What seems new is the fact that some labour reforms are now being built by the government and trade union organisations. In France, this is the consequence of a 2007 reform that makes it able the French trade unions to draw up a reform agenda regarding particularly trade union representativeness, collective bargaining (law renewing social democracy in 2008, law on social dialogue in the civil service), the financing of trade unionism (law on professional training, employment and social democracy). This communication proposes to analyse the making and the implementaition of these various reforms and, through it, to understand the new nature of trade unionism. We could talk about a new style of corporatism that has succeeded in asserting its conception of social democracy. This social democracy is now under the control of a cartel of trade union organisations (this ‘model’ is very similar than the one of Katz and Mair for political parties). It also tends to make unions less dependent on their members. It therefore confirms their institutionalization and the professionalization of their leaders. Of course, this new ‘model’ does not exclude tensions with the government. When reform projects are not appropriate for trade unions, they refuse negotiation and favour collective action (demonstrations or strikes). But in recent years, this strategy has failed and unions finally prefer face-to-face negotiations and preserve their cartel.