Can they prove legal residence throughout the requisite period? For these facts to be legally accepted, civil registration documents will almost always be necessary; and if the birth of the child or marriage of the parents—or death of a parent, if relevant—took place in another country, then it will often be necessary to obtain a certificate from that country, and also have it legally recognised in the country where nationality is claimed (see next sub-heading). If the most important identity documents or proof of residence are missing for recognition of nationality of the state of residence, it may in some contexts—especially in those countries where many people do not have identity documents—be possible to adduce evidence based on voter registration (usually an acknowledgement that the person is a national), or registration in other functional registers. Immigration and other documents about existing legal status in the country, and the treatment of the person in practice by relevant authorities, will often be critical. Private international law In statelessness cases, the complexity of the necessary arguments is often increased by the need to also consider the nationality (and related) laws of other countries, and the questions of private international law (conflicts of law) by which they should be interpreted in the relevant jurisdictions.101 If a civil status event—birth, adoption, marriage, divorce, death—takes place in a different country from the one where nationality is being claimed, it is often necessary to acquire official copies of civil status documents from the other country and submit them in a form accepted by the authorities of the country of nationality, usually by transcription into its national civil status records. If the events were not registered in the other country, national law may or may not provide for their late registration or substitution by other procedures. Moreover, a finding of an error at any stage in these processes can sometimes result in the retroactive loss of nationality apparently legitimately held over many years.102 In some contexts, if it is being argued that a person should receive recognition of nationality or protection as a stateless person in the country of residence, it may be a requirement to prove a negative through the same processes—that the person concerned is not “considered as a national” by any other country (the definition of stateless person in international law).103 To make these arguments, it will very often be necessary to secure expert evidence about the law of the other country or countries to which the person has a connection, and its interpretation by the authorities and courts of that country. The identification of relevant experts should start early in the litigation process (u section 5.4: Expert opinions). Comparative law Arguments from comparative law are not always welcomed in national courts. However, at minimum, a case decided by an apex court in another country may be used to show how a particular interpretation of the law has been found outmoded elsewhere, or to suggest a remedy, or simply to demonstrate that what the complainants are calling for is reasonable and accepted in other jurisdictions. This type of argument is perhaps more likely to be accepted in the common law jurisdictions, where case law plays a stronger role—and it is particularly powerful among those countries that were former British territories and shared the nearly standardised legal regime for citizenship that was negotiated with all these states on gaining independence. For example, the Unity Dow case from Botswana, in which the Court of Appeal found that discrimination on the basis of sex in transmission of citizenship to children and spouses was unconstitutional,104 has been extensively cited in other courts105; and was used in the arguments made by plaintiffs in a case before the Malaysian courts challenging discrimination against women in transmission of citizenship to their children born outside the country.106 Even in the civil law context, however, such precedents are useful: the Chilean Supreme Court was cited by the Colombian Constitutional Court in a case concerning the nationality of children of Venezuelan refugees born in Colombia.107 Public international law It is very common for governments to assert the statement in Article 1 of the 1930 Convention on the Conflict of 101 Bronwen Manby, “Legal Identity for All’ and Statelessness: Opportunity and Threat at the Junction of Public and Private International Law”, Statelessness and Citizenship Review vol. 2, no. 2 (2020), pp.248–71. Gerard-René de Groot and David de Groot, “Recognition of Civil Status (Certificates), with Special Attention to Secondary Recognition of Documents Already Recognised in Another Member State”, in Researches in European Private Law and Beyond-Contributions in Honour of Reiner Schulze’s Seventieth Birthday, ed. André Janssen and Hans Schulte-Nölke (Baden-Baden: Nomos, 2020). 102 103 Convention Relating to the Status of Stateless Persons, 1954, art. 1(1). 104 Attorney-General v. Dow, Botswana Court of Appeal, Judgment of 3 July 1992, 1992 BLR 119 (CA). 105 Discussed in Karen Knop and Christine Chinkin, “Remembering Chrystal MacMillan: Women’s Equality and Nationality in International Law’, Michigan Journal of International Law Vol.22, no. 4 (2001) pp. 523–86, at pp. 533–534 & p. 554. 106 Family Frontiers, interview for evaluation of OSJI support for litigation on access to citizenship and identity documents, February 2022. 107 Sentencia T-006/20, supra n 29, pp. 22-23, 58. 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