 Russia being a successor state to the Soviet Union, all former USSR citizens qualified for citizenship of Russian Federation, available upon mere request, as provided by the law "On the RSFSR Citizenship" in force up to end of 2000.Estonia's policy of requiring naturalisation of post-war immigrants was in part influenced by Russia's citizenship law and the desire to prevent dual citizenship, and upon the established legal principle that persons who settle under the rule of an occupying power gain no automatic right to nationality.According to Peter Van Elsuwege, a scholar in European law at Ghent University, a number of historic precedents support this, most notably the case of Alsace-Lorraine when France on recovering the territory in 1918 did not automatically grant French citizenship to German settlers despite Germany having annexed the territory 47 years earlier in 1871.