This article joins the nascent debate on the causal status of securitisation theory. Relying on critical realist’s efforts to deepen and broaden the concept of cause – defined as ‘causal complex’ – and its insights to integrate discourse and constitutive relations into a non-positivist framework for causal explanation, the article aims to explore the explanatory status of securitisation theory, without downgrading its discursive core. To illustrate this argument, the article uses the securitisation of Somali piracy as an example of how the causal analysis of securitisation can contribute to explain some of the dynamics involved in security governance. From this perspective, securitisation works within a broader empirical framework of security, significantly implicated in causal relations, going beyond the Copenhagen School’s conception of securitisation as a non-causal constitutive theory merely defined as a formal framework for analysis. The article discusses, finally, the relevance and implications of introducing causal analysis in the study of securitisation.

Combating piracy at sea and apprehending pirates have been a long-standing problem for the global community. Increasing acts of piracy off the coast of Somalia have prompted the UN Security Council to intervene in the matter. The Council, through several resolutions, has authorised states to take action against Somali pirates in the territorial waters and land territory of Somalia and recently adopted a resolution urging all states to fully implement relevant international conventions in their domestic legal systems. However, despite the Security Council's intervention in the matter most states are still reluctant to prosecute Somali pirates in their domestic courts. Considering the most recent Security Council resolution and existing international law, this article examines whether there is an international obligation to criminalise piracy under domestic legal frameworks and to prosecute pirates in domestic courts. It submits that existing international law arguably imposes an obligation to prosecute pirates, at least in certain circumstances, and the recently adopted Security Council resolution reinforces this obligation.