Provisions for a parliamentary investiture vote have become increasingly common in parliamentary democracies. This article shows that investiture provisions were largely introduced when new constitutions were written or old ones fundamentally redesigned. It also shows that the constitutions that endowed executives with strong legislative agenda powers also endowed parliaments with strong mechanisms to select the executive. It is argued that constitution makers’ decisions can be seen in principal–agent terms: strong investiture rules constitute an ex ante mechanism of parliamentary control – that is, a mechanism to minimise adverse selection and reduce the risk of agency loss by parliament. The findings have two broad implications: from a constitutional point of view, parliamentary systems do not rely exclusively on ex post control mechanisms such as the no confidence vote to minimise agency loss; parliamentarism, at least today and as much as presidentialism, is the product of conscious constitutional design and not evolutionary adaptation.
West European Politics; Vol. 38, issue 5, 2015.