While significant research has been conducted on both the diffusion of democracy and the various democratic government systems (parliamentary, presidential and semi-presidential), the diffusion of individual democratic government systems has rarely been addressed. Therefore, this article examines whether diffusion explains why countries have established different types of government systems at the time of democratisation. Previous studies on democratic regime types have found that the establishment of democratic government systems is spatially and temporally clustered, which could indicate that democratic regime types are diffused. Inspired by diffusion studies, we test the hypothesis that the density of a particular democratic government system in a network positively affects the probability that a country in that network established the same form of democratic government system at the time of democratisation. We test this assumption through empirical analysis, using 121 cases of democratisation in which a democratic system of government was established at the time of independence or after a period of autocracy. Using logistic regression, this paper explores the connection between the choice of government system at the time of democratisation and the composition of democratic government systems in seven networks of countries: geographic neighbourhood, regional, continental, global, cultural, post-colonial and post-autocratic. The results indicate empirical support for our hypothesis; therefore, we conclude that the choice of government system at the time of democratisation is influenced by conditions in other countries.

This study maps the general lines of semi-presidential research with regard to theory, topics and methods. It identifies research gaps and provides recommendations for future studies. The review includes a general screening of 327 publications covering the period 1970-2015, and a close reading of sixty-five selected publications. The findings suggest that the inconsistent use of regime type definitions has limited the possibilities for generalizations. The study tracks the influence of some seminal articles, as well as the recent trend of focusing on the role and powers of the president. The article calls for more studies beyond Europe, and suggests that the field would benefit from including Historical and Normative Institutionalism. Finally, it suggests the need for studies on public administration that are relevant to the functioning of semi-presidential government.