My research was based on the archives of the Organisation for Economic Co-operation and Development, the Council of Europe, and the European Union. I scrutinised a large number of documents on European negotiations, including for the most recent period, thanks to declassifications. This allowed me to maintain my methods of historian and at the same time cover recent developments. I also examined the national archives of the French Ministry of the Interior, the French Presidency of the Republic under Francois Mitterrand, the German political archives in Berlin, and official publications from the European Commission, the European Parliament, the World Bank, and the United Nations.
Few had so far studied the history of the European migration regime and they had analysed the role of emigration countries, e.g. Italy. In my research, I have highlighted the leading role Germany played in the construction of the current European migration regime. The German economy disproportionately absorbed most of the new migrants created by the open migration regime and transferred the bulk of social security benefits abroad for these same migrants (unemployment benefits, pensions, and family allowances). Far from being a secondary concession to the governments of emigration countries, I show how the openness of the European migration regime was a central aspect of German geopolitical and geo-economic strategy in Europe during the Cold War.
An open migration regime was to offer opportunities, diminish social tensions, and reduce support for Communism in peripheral but geographically strategic countries of Western Europe. By doing so, it was to reinforce the cohesion of Western Europe, which was vital to increase the bargaining power of Germany towards the Soviet Union and achieve Reunification. I show how the open migration regime stemmed from the concern of German authorities in the early 1950s to be in position to absorb waves of refugees from East Germany whatever the economic conditions in West Germany could be. The support of other countries could be decisive in certain cases and such absorption was a key instrument to weaken Communist governments in Eastern Europe. More broadly, the open migration regime in Western Europe epitomized the liberal international order and acted as a magnet for the populations of Eastern Europe. The same rules of the open migration regime were finally strategic to favor the expansion of German firms in other European countries, by removing visa requirement, obstacles to establishment, as well as the non-recognition of qualifications and certificates.