Despite the historical disapproval of multiple citizenships, policies and opinions of many countries on citizenship are shifting as the world environment and attitudes have changed considerably. The rise of globalization has encouraged a greater movement of people locally and internationally. As a consequence, the notion of dual nationality - the act of having citizenship in two countries at the same time- is emerging throughout the world. Dual nationality is a result from the fact that there is no uniform rule of international law relating to the acquisition of nationality. Each country has its own laws on the subject, and its nationality is conferred upon individuals on the basis of its own independent domestic policy. Individuals may have dual nationality not by choice but by automatic operation of these different and sometimes conflicting laws. There are also a number of Thai nationals with dual status residing in both Thailand and overseas due to an increase in number of intermarriage and out-migration of Thai people. The study finds that, according to Thailand's nationality law, there are many ways for a Thai national to obtain dual nationality, both at birth – based on the jus soli principle and the jus sanguinis principle; and after birth – through marriage with an alien spouse and through naturalization. To a certain extent, Thailand does recognize the concept of dual nationality, as there are no provisions which state that the persons with dual nationality required at birth are illegal or would be punished for holding such status. However, a Thai national who holds dual status through naturalization will be considered as an alien, according to the law, they would lose Thai nationality if the Government Gazette has been published. The study finds that one of the main reasons that drives0. an individual to acquire dual nationality is the economic benefits they could gain for having dual status, including being protected under the laws and regulations of the country of their nationality and being able to gain rights and access to the resources that a national of a particular country is entitled to. At the individual level, having dual nationality is seen to be more beneficial than problematic. This contrasts with the consideration of the Thai state towards dual nationals that may abuse the advantages gained from having dual nationality in a wrong way, particularly people who are involved with transnational crimes, terrorist groups, and separatist movement which are the main threat to the national security. From this perspective, there is still a need of cooperation between Thailand and other states to deal with dual nationality issue, in order to manage and monitor the number of persons with dual nationality in Thailand and abroad for future development of the country.
