. Identification re ention and reduction o state essness as a result of sexual exploitation and abuse. It is also difficult to properly register those children whose parents are undocumented themselves, no matter where they are born. Birth registration is also relevant to the protection of a range of other rights, including education, preventing child marriages, trafficking and other forms of exploitation, and the recruitment of children into armed forces or armed groups. States, therefore, have a two-fold interest in birth registration: to prevent statelessness and as a protection tool. Where necessary, States can work together with agencies specialized in this field, such as UNHCR, the United Nations International Children’s Emergency Fund (UNICEF), the United Nations Population Fund (UNFPA) and many other organizations, to ensure that all persons are registered at birth.75 Most States issue nationality certificates or identity cards that attest nationality76 and, in many countries, a passport is also considered proof of nationality. In order to address risks of statelessness arising from difficulties in proving nationality, States need to ensure accessible procedures for the issuance of nationality documentation, and simplify evidentiary requirements. Simplifying procedures and evidence requirements Sometimes States have strict and numerous evidence requirements that impede the registration of births and/or the issuance of nationality documents. For example, the parents’ marriage certificate, the birth certificate of both parents, and the valid residence permit of both parents can all be required before a child’s birth can be fully registered. Sometimes even the grandparents’ identity papers are required to register a child’s birth. Difficulties in meeting such requirements may leave the child without any proof of legal identity for a long time or even indefinitely.77 Simply waiving or lifting some of the requirements (e.g. the parent’s marriage certificate and the parents’ birth certificate) would contribute considerably to simplifying birth registration processes. Another way that birth registration can be improved is through the facilitation of (late) birth registration with the use of witnesses and testimonies instead of documentary evidence. This allows older children or adults to have their birth registered even though they do not meet the formal requirements for (late) birth registration.78 54