stresses the importance of international co-operation and the conduct of friendly relations in dealing with concerns about people or situations in other States. 11. States may take preferred linguistic competencies and cultural, historical or familial ties into account in their decision to grant citizenship to individuals abroad. States should, however, ensure that such a conferral of citizenship respects the principles of friendly, including good neighbourly, relations and territorial sovereignty, and should refrain from conferring citizenship en masse, even if dual citizenship is allowed by the State of residence. If a State does accept dual citizenship as part of its legal system, it should not discriminate against dual nationals. The conferral of citizenship is generally considered to fall under the exclusive domestic jurisdiction of each individual State and may be based on preferred linguistic competencies as well as on cultural, historical or familial ties. When this involves persons residing abroad, however, it can be a highly sensitive issue. Contested claims or competing attempts by the States concerned to exercise jurisdiction over their citizens, irrespective of the place of residence, have the potential to create tensions. This is particularly likely to happen when citizenship is conferred en masse, i.e. to a specified group of individuals or in substantial numbers relative to the size of the population of the State of residence or one of its territorial subdivisions. States should therefore refrain from granting citizenship without the existence of a genuine link between the State and the individual upon whom it is conferred, as ruled by the International Court of Justice in the Nottebohm Case (1955 I.C.J. 4). Even though States have the right to freely determine who their citizens are, they should not abuse this right by violating the principles of sovereignty and friendly, including good neighbourly, relations. Full consideration should be given to the consequences of bestowing citizenship on the mere basis of ethnic, national, linguistic, cultural or religious ties, especially if conferred on residents of a neighbouring State. It could for example lead to differential treatment for these individuals as compared with other residents of the “kin-State” who may be denied access to citizenship. Article 5 of the 1965 UN Convention on the Elimination of All Forms of Racial Discrimination and Article 5 of the 1997 European Convention on Nationality provide that the rules of a State on citizenship must not contain distinctions or include any practice that constitutes discrimination on the grounds of, inter alia, national or ethnic origin. Recommendations on National Minorities in Inter-State Relations 19