As stated by the ILC in its commentary to draft Article 19(1): (1) Paragraph 1 safeguards the right of States other than the State which has attributed its nationality not to give effect to a nationality attributed by a State concerned in disregard of the requirement of an effective link. International law cannot, on its own, invalidate or correct the effects of national legislation on the nationality of individuals, but it allows “some control of exorbitant attributions by States of their nationality, by depriving them of much of their international effect”, because “the determination by each State of the grant of its own nationality is not necessarily to be accepted internationally without question”. In the final analysis, although nationality pertains essentially to the internal law of States, the general principles of the international law of nationality constitute limits to the discretionary power of States. (2) The need to “draw a distinction between a nationality link that is opposable to other sovereign States and one that is not, notwithstanding its validity within the sphere of jurisdiction of the State [in question]” has led to the development of the theory of effective nationality. As regards the specific situation of a succession of States, it is also widely accepted that [t]here must be a sufficient link between the successor State and the persons it claims as its nationals in virtue of the succession, and the sufficiency of the link might be tested if the successor State attempted to exercise a jurisdiction over those persons in circumstances disapproved of by international law, or attempted to represent them diplomatically; provided, that is, there is some State competent to protest on behalf of the persons concerned. (3) A number of writers on the topic of the succession of States who hold the above view that the successor State may be limited in its discretion to extend its nationality to persons who lack an effective link with the territory concerned base their argument on the decision of ICJ in the Nottebohm case. In its judgment, the Court indicated some elements on which an effective nationality can be based. As the Court said, [d]ifferent factors are [to be] taken into consideration, and their importance will vary from one case to the next: the habitual residence of the individual concerned is an important factor, but there are other factors such as the centre of his interests, his family ties, his participation in public life, attachment shown by him for a given country and inculcated in his children, etc. It is to be noted, however, that the Italian-United States Conciliation Commission, in the Flegenheimer case, concluded that it was not in its power to deny the effects at the international level of a nationality conferred by a State, even without the support of effectivity, except in cases of fraud, negligence or serious error. Moreover, the judgment in the Nottebohm case only dealt with the admissibility of a claim for diplomatic protection and did not imply that a person could be generally treated as stateless. (4) In practice, different tests for determining the competence of the successor State to attribute its nationality on certain persons have been considered or applied, such as habitual residence or birth. Thus, for example, the peace treaties after the First World War as well as other instruments used as a basic criterion that of habitual residence. But, as has been pointed out, “[a]lthough habitual residence is the most satisfactory test for determining the competence of the successor State to impress its nationality on specified persons, it cannot be stated with assurance to be the only test admitted in international law”. Some authors have favoured the test of birth in the territory affected by the succession as proof of an effective link with the successor State. In recent dissolutions of States in Eastern Europe, the main accent was often put on the “citizenship” of the component units of the federal State that disintegrated, which existed in parallel to federal nationality. (5) The term “link” in paragraph 1 of article 19 is qualified by the adjective “effective”. The intention was to use the terminology of ICJ in the Nottebohm case. Although the question of non-opposability of the last part of the paragraph could be amended to read: ‘and this would result in treating them as stateless’, or words to that effect” (see International Law Commission, “Summary Record of the 2486th meeting”, A/CN.4/SR.2486, 30 May 1997, para. 70). 59