"Regime of Convention: The Swiss Case" is an introduction to a conventional theory carried out to practice, by means of a description of a concrete case regarding the structure of a conventional government and its distribution of powers. The regime of convention (or conventional) is a government system that is based mainly in the concordance and in the agreements. Members of the majority of the political institutions (especially at a federal level) are appointed or elected by a superior entity, which to a great extent monopolizes both the legislative and the executive branches. This governmental system is the system that for a long time has characterized the Helvetian Confederation (Switzerland). Given that as a theory it is much more ancient than parliamentarism or presidentialism.