Jus soli

Jus soli (Latin for "right of ground"), also known as birthright citizenship, is a system in which nationality and/or citizenship is granted to any and all persons born within the territory of, and subject to the jurisdiction of, a state. Jus soli citizenship policies are mostly found in the Western Hemisphere.

Jus sanguinis
Jus soli differs from jus sanguinis (Latin for "right of blood"), wherein nationality and/or citizenship is granted to persons whose parents were citizens of a country. Jus sanguinis in addition to being blatantly racist — it for instance gives more rights to, hypothetically, descendants of 17th century emigrants that don't live in the country or speak the language than third-generation immigrants who know no other home on account of their "blood" — is also highly illogical. All human beings are immigrants or the descendants thereof with the exception of possibly a few people in East Africa, hence any "American blood" a citizen could possibly have is only determined by an ancestor of that person having immigrated to the US at some point — most likely after 1492. Unfortunately very few countries have newly introduced unlimited jus soli in the last couple of decades and many — like Ireland — have actually struck previous jus soli from the books or restricted it by requiring the parents to possess certain traits for it to apply. As if children were to blame for the migratory or marital status or the skin color of their parents. Of course, logic does not often enter the mind of "keep out those ferriners" types.

United States of America
In the United States, it is affirmed in the first section of the Fourteenth Amendment: All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.

Jus soli has become the subject of much debate because it makes the children of illegal immigrants US citizens. This has caused anti-immigrant conservatives such as Donald Trump and Texas Lieutenant Governor Dan Patrick to call for a change to the amendment and to denigrate US citizens ("anchor baby"), rather than actually fix the immigration issue. How those conservatives intend to then pass a citizenship test, especially in light of their own lack of knowledge about U.S. history and the Constitution, is not yet known.

In the world
Several states in Europe, Asia, Africa and Oceania grant citizenship at birth based upon the principle of jus sanguinis or a restricted version of jus soli in which citizenship by birthplace is automatic only for the children of certain immigrants.

No country in the European Union grants automatic and unconditional citizenship to children born in their territories to foreign citizens, and only 10 of 28 countries have some form of conditional jus soli, including Britain, Belgium, Germany, Ireland, and Portugal. The most common condition for jus soli is that parents should have resided in the country for a certain period of time before the child’s birth (conditional jus soli), or that at least one of the parents was also born in the country (double jus soli).