nationals are denied all identity documents which prove nationality.17 In addition, actions by officials that do not have formal legal authorisation, such as confiscation or destruction of identity documents and/or expulsion from the territory, together with statement by authorities that a person is not a national, would also be evidence of withdrawal of nationality.18 Where a State repeals or restricts with retroactive effect a legislative ground for acquisition of nationality, persons who possessed the nationality of the State concerned may be deemed by the State never to have acquired its nationality. The effect is that these persons are deprived of nationality. The same applies to deprivation of nationality in a concrete case with retroactive effect. Participants of the Expert Meeting for the Tunis Conclusions agreed that this is deprivation rather than nonacquisition of nationality. These situations therefore fall under the Articles 5-8 of the 1961 Convention, a conclusion supported by the travaux préparatoires.19 Similarly, the 2020 UNHCR Guidelines No. 5 on the 1961 Convention state that any legislation relating to the deprivation of nationality should be “in line with the general principle that a person may not be tried for conduct that was not an offence at the time the conduct occurred. 20 The same conclusion is to be drawn in all cases where a State ex post claims that the conditions for acquisition were never fulfilled, for example where it is established that the conditions which led to the automatic (ex lege) acquisition of the nationality were not satisfied.21 12. The revocation of passports and the imposition of travel or entry bans are not the same as the deprivation of nationality. However, such measures are often implemented together with the measure of deprivation of nationality or may be indicative that the State has ceased to consider an individual as a national, and such decisions should be subject to these Principles. The withdrawal or refusal to renew a passport or other travel document in relation to a person who is currently outside the borders of that State may, in some circumstances, be considered to constitute deprivation of nationality. On this matter, please also refer to the Commentary on Principle 10 on deprivation by proxy and proxy measures. 13. The African Court has found that in cases where a State denies or invalidates an individual’s documents proving nationality held from birth the burden of proof lies with the State: “since the Respondent State is contesting the Applicant’s nationality held since his birth on the basis of legal documents established by the Respondent State itself, the burden is on the Respondent State to prove the contrary. 22 If the State is refusing to issue nationality documents on the basis that the individual is in fact a national of another state and has in the past or is trying to fraudulently acquire nationality documents to the refusing state, the burden is on the state to produce “concrete evidence to support its assertion that the Applicant has other nationalities. 23 17 UNHCR, ’Tunis Conclusions‘ . UNHCR, ’Tunis Conclusions‘ , para . 19 UNHCR, ’Tunis Conclusions‘ , para ; see also Travaux Preparatoires of the 1961 Convention on the Reduction of Statelessness, available at : https://legal.un.org/diplomaticconferences/1959_statelessness/ 20 UNHCR Guidelines No 5 (2020), para 93. 21 UNHCR, ’Tunis Conclusions‘ , para . 22 ACtHPR, Anudo v Tanzania (2018), Application no. 012/2015, para 80, available at: https://en.african-court.org/index.php/56-pending-casesdetails/877-app-no-012-2015-anudo-ochieng-anudo-v-united-republic-of-tanzania-details; see also ACtHPR, Robert John Penessis vs United Republic of Tanzania, Application No 013/2015, Para 92 ff: available at: https://www.africancourt.org/en/images/Cases/Judgment/YJudgement%20in%20the%20Matter%20of%20Robert%20John%20PENESSIS%20Vs%20United%20Repu blic%20of%20Tanzania%20Delivered%20on%2028%20November%202019%20-%20Optimized.pdf 23 See ACtHPR, Robert John Penessis vs United Republic of Tanzania, Application No 013/2015, Para 102. 18 24