A decade and a half after the democratic transition in the countries of central and eastern Europe, the Venice Commission marked its fifteen years of existence by looking back over this period of institutional upheaval.The Warsaw seminar, which inaugurated the work of the Polish chairmanship of the Committee of Ministers of the Council of Europe, viewed these fifteen years of change in the light of constitutional practice. Thus, two basic approaches were adopted: the role of the executive in this practice, and the influence of electoral systems in institutional change.The papers and discussions in Warsaw brought together specialists from very different backgrounds. Marking a convergence between constitutional law and electoral law, this conference retraced fifteen years over which the outlines of powers have gradually taken shape. Depending on the state, the executive has moved towards a presidential, semi-presidential, or parliamentary form of government, with a trend towards the latter two.During this period, electoral systems underwent major changes, sometimes dictated by general interest and sometimes responding to partisan demands. In all institutions the electoral systems have kept pace with constitutional practice and change, and have thus led progressively towards honest and genuine choices for citizens.