ABSTRAK
Tesis ini bertujuan untuk mendeskripsikan dan menganalisis pengaturan batas usia dewasa dalam sistem hukum Indonesia menurut Hukum Perdata, Hukum Pidana, Hukum Tata Negara, Hukum Islam, Hukum Adat dan Hukum Administrasi Negara serta pengaruh penetapan batas usia dewasa dalam administrasi kependudukan dihadapkan pada masalah kewarganegaraan. Berdasarkan hasil penelitian diperoleh bahwa pengaturan batas usia dewasa dalam sistem hukum Indonesia berbeda-beda. Perbedaan tersebut mengakibatkan ketidakpastian hukum yang berimplikasi negatif terhadap penegakan hukum di Indonesia. Pembatasan hak pilih anak kewarganegaraan ganda yang berindikasi pada pelanggaran hak asasi manusia. Oleh karena itu, perlu penyelarasan batas usia dewasa di dalam sistem hukum, khususnya peraturan perundang-undangan di bidang Hukum Administrasi Negara.

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ABSTRACT
This thesis is to describe and analyze determination of adult age limit on Indonesia legal system according to the Civil Law, Criminal Law, Constitutional Law, Islamic Law, Customary Law and Administrative Law as well as the effect of the determination of adult age limit on the population administration faced with the problem of citizenship. Based on the results of research shows that determination of adult age limit on Indonesian legal system is different. Such differences lead to legal uncertainty which has negative implications on the law enforcement in Indonesia. Restrictions on voting rights of child who has dual citizenship which indicate the violation of human rights. Therefore, it is necessary harmonization of the adult age in the law system, especially legislation in the field of Administrative Law.