Countries in general define citizenship based on one’s descent, place of birth, marriage, and/or naturalization. That is, you might be a citizen of a given country for one or more of the following reasons:
- You were born on territory belonging to, or claimed by, that country.
- One or both of your parents were citizens of that country (right of blood).
- You married a citizen of that country.
- You (or one or both of your parents) obtained that country’s citizenship by going through a legal process of naturalization.
However, US limits its application of right of blood by requiring American parents to have lived for a certain period of time in the US before foreign-born children can be entitled to US citizenship by birth.
Since there can be several ways to acquire a given country’s citizenship, it is possible for someone to be considered a citizen under the laws of two (or more) countries at the same time. This is what is meant by dual (or multiple) citizenship.
Countries usually frame their citizenship laws with little or no regard for the citizenship laws of other countries. Sometimes a country may seek to restrict dual citizenship by requiring one of its citizens born with some other citizenships to renounce the other citizenship upon reaching adulthood. Newly naturalized citizens may similarly be required to renounce their previous citizenship(s); the US has such a requirement, for example but Canada does not. Where one country requires a citizen to renounce the citizenship of another country, this renunciation may or may not be recognized by the other country. Us will not treat their own naturalization oaths’ renunciatory language as essentially meaningless and take no steps to enforce it all.
Dual citizens are not entitled to any sort of special treatment by their two countries of citizenship. Each country will usually consider the person as if he were a citizen of that country alone. India too very soon going to permit dual citizenship, but the details are yet to announced by the Government of India.
Citizenship frequently carries with it legal obligations relating to taxes, military service, and/or travel restrictions. A dual citizen may have to pay taxes (in addition to taxes he is already paying in his country of residence); considers him liable to be drafted into its army. In practice, such situations are often ironed out over via tax treaties and the like, but conflicts could sometimes occur.
Citizenship claims by a country over a given individual could happen even if the person in question never sought recognition as a citizen of that country – or even if the person is totally aware that s/he was a citizen of that country according to its laws. Therefore, anyone who is planning to travel to an ancestral homeland even for a brief vacation trip – is strongly advised to check that country’s citizen laws carefully beforehand.
However, a dual citizenship can have distinct advantages. In particular, a person with dual citizenship has greater flexibility in his or her choice of where to live and work. It is therefore advised that persons who intend to obtain dual or multiple citizenship all the pros and cons of such status.