Nationality Laws and what most people don't know or understand that affects them
Here is a topic that is often overlooked by the general population. Particularly but not limited to residents and immigrants to the US. Nationality laws play a role on how a country decide who should be its subjects or not and also who is entitled to abode and protection in its country. A person might inherit a countries nationality or citizenship by different ways. These ways include Jus Soli(right of the land) which birth in a country that provides automatic citizenship for all births within the country or its territories and Jus Sanguinis(right of the blood) when the nationality or citizenship is transmitted according to the parent's nationality no matter where the child is born. Most all countries operate under the principle of Jus Sanguinis however much fewer also operate under the principle Jus Soli these countries are mostly in North, Central, and South America. Some countries in Europe such as Ireland and Spain operates under a limited Jus Soli principal. Those countries had scaled it back to combat illegal immigration tactics of anchor babies. All Jus Soli countries also have Jus Sanguinis provisions however most countries in the world only have Jus Sanguinis provisions.
While most people in the US is kind of aware of Jus Soli even if they don't know this term. They know that one born here is automatically a citizen no matter the immigration status of the parents. Though they might not be aware of Jus Sanguinis or right of the blood. For example one can ask many immigrants whose child is born in they US a good chance is that they might have no idea that their child may be considered a citizen in their old country. Many may think that there children don't have their old country's citizenship. However the laws of their old country might say otherwise and the details can very country to country and some can be hard to comprehend. It can involve some complications as the Master nationality rule of article 4 of the Hague convention that relates to conflict of nationality laws. The laws of the country that person is considered a nationality would prevail even over laws of the person's other nationality if he/she happens to be in that country's territory. In this case even the concept of diplomatic immunity is suspended if the diplomatic personnel happen to be assigned to a country of his "other" nationality. The nationality rule applies regardless of which country the subject primarily lives and which passport he used to enter. For example a child born in China or abroad entitled to Chinese citizenship at birth would need to depart China with not only a Chinese passport but an exit permit as required for all citizens to depart China. Even if the child primarily lives in the US and carries a US passport. He would not be allowed to depart China with a US passport. Countries such as Poland those considered citizens to leave the country using only Polish travel documents. Unsuspecting tourists who had no idea they are considered Polish due to a grandparent holding citizenship might get detained in Poland for this reason as Polish nationality laws extends to an unlimited generations. This rule also affects immigrants who move to another country to escape military service requirements. There are a number of people who intentionally move of their home country to avoid military draft and not return as promised and think they can return after obtain their other country's passport to hide from the draft ended up arrested for draft dodging and have to complete the service upon return to the country.
Though Jus Sanguinis may also have positive impacts for a child. For example if the child wants to return to live in their parent's country he or she is entitled to the "right of abode" in that country meaning that they don't have to go through the immigration process if they decide to live and work in their parents' country. Also now a days it pays to have a second passport regardless even if one does not plan to move to the other country. A second passport allows greatly increased economic freedom and can make immigrating to a third country much easier as sometimes countries favor immigration for certain countries more than others. The difference in visa fees and visa free access list can easily prove this discrepancy. For example it is currently very difficult to travel let alone apply for immigration with a ordinary mainland Chinese passport and many countries require visas for Chinese citizens which are expensive, hard to get, and often denied with no valid excuse, in this case though if a child with mainland Chinese citizenship also has a second citizenship by descent from another country such as Japan, Britain, or most European countries that he or she inherited from the child can use the other passport to travel and immigrate. The privilege of another citizenship would usually cost one at least $35000 - $50,000 and may often involve immigration and residency both a hassle. Therefore the child would be very lucky for the privilege without going through all the hassle. Though beware certain countries such has Japan require the child be registored within a certain time frame in order to claim birth citizenship if they acquired a foreign citizen by birth in the country abroad. Therefore it is best to find out about the child's entitlement shortly after birth. Also few countries i.e Japan has a requirement that requires dual national children choose their nationality by a certain age though it may be possible to retain dual citizenship by using some pearls of wisdom such as only representing to the country as that country's citizen and not showing that you are another country's citizen.