If political violence is – as I argued in the previous chapter – related to cycles of protest and the evolution of social movements, causal explanations for its development have to be found in the processes and structures that more directly affect social movements and protest. This chapter is devoted to the influence of the political system on protest escalation. Like other features of social movements, protest repertoires – and therefore violence – are related to contextual, macro-variables. As mentioned in Chapter 1, several hypotheses on the preconditions for violence referred to political variables. Blocked political systems and state delegitimation are explanations often quoted to account for both the Italian and German terrorism.

The relationship between social movements and the state is a most crucial theme for the understanding of collective action. Long neglected, it acquired a new relevance with the development of the “political process” approach to social movements (Tilly 1978, 1984; McAdam 1982). Within this approach, as I already observed, the political opportunity structure (POS) (Eisinger 1973; McAdam 1982; Tarrow 1983) is the most inclusive concept we have for dealing with the external, political conditions for protest. In this chapter, I discuss political opportunities for social movements in Italy and the Federal Republic of Germany after World War II, focusing on protest policing and its effect on the action repertoires of social movements.