Citizenship may be acquired according to two methods—(i) by birth, or (ii) by naturalization.
There are two practices which are observed regarding the acquisition of citizenship by birth—Jus Sanguinis and Jus Soli.
According to Jus Sanguinis, a child acquires the citizenship of parents irrespective of the place of birth, e.g., child born of Indian parents is an Indian citizen whether it is born on Indian soil or abroad. The practice of Jus Sanguinis was very popular in ancient times.
Even now, it is observed by most of the states in the world. This practice is natural as well as logical. It is exclusively observed in Germany, Italy, Sweden, Norway etc.
According to this practice, citizenship is determined by the place of birth and not by parentage. This practice is now not popular. It was, of course, popular in the middle ages when citizenship was associated with land. At present, however, this practice is exclusively observed in Argentina.
In England, U.S.A. and France, both the above practices are employed simultaneously. Observance of both the practices sometimes gives rise to duplication of citizenship. A child born of English parents in America, for example, becomes the citizen of America according to the practice of Jus Soli.
The same child becomes a citizen of England also according to the practice of Jus Sanguinis. The problem is solved by giving an option to the child to accept the citizenship of either state it likes when it comes of age.
Citizenship can also be acquired through naturalization. According to this method, an alien can become a citizen after fulfilling certain conditions. Though these conditions vary from state to state, yet some of the general principles which are observed may be summed up as follows:
A certain period of residence in the state is essential before an alien can be granted citizenship. This period varies from state to state.In England and U.S.A. this period is 5 years. In France, it is 10 years.
2. Oath of Allegiance:
An alien must take an oath of allegiance before he can become a citizen of another state.
3. Purchase of Real Estate:
An alien, who buys real estate in a foreign land, can get the rights of citizenship if he so desires.
4. Service (Civil or Military):
An alien my be given rights of citizenship if he renders meritorious service in another state.
Women acquire the citizenship of their alien husbands e.g., an English lady will acquire the citizenship of India if she marries an Indian.
The condition of marriage in Japan, however, is quite different. Japanese women do not lose their citizenship even if they marry alien husbands. The alien husband, on the other hand, acquires the citizenship of Japan if he marries a Japanese lady.
Loss of Citizenship:
Citizenship may be lost under the following conditions.
One may renounce the citizenship of one's original state and may become the citizen of a foreign state by naturalization.
Women lose the citizenship of their original state if they marry aliens. In England, there is a move to retain English citizenship for women marrying foreigners.
3. Acceptance of Service, Decoration or Title from a Foreign State:
Some states deprive their citizens of citizenship, if they accept service, honor or title in a foreign state.
4. Long Absence:
In some state, like France and Germany, citizens who absent themselves from their states for more than ten years may lose their citizenship.
5. Treason or Felony:
A person, who is charged with treasonable activities, may be deprived of his citizenship.