Donald Trump slams 'birthright citizenship.' Why does US even have it?

Several Republican presidential candidates, including front-runner Donald Trump, have railed against birthright citizenship in the context of illegal immigration. Here's the legal background for the concept.

Fears over illegal immigration and "anchor babies" have led several Republican presidential candidates – including front-runner Donald Trump – to rail against a significant part of the 14th Amendment to the Constitution.

Section 1 of the 14th Amendment – named the citizenship clause – grants automatic citizenship to people born in the country.

“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,” the amendment states.

The criticism of the clause from the GOP candidates centers on the automatic granting of citizenship to a child whose parents are in the country illegally, an idea known as "birthright citizenship."

But where did this privilege even come from?

When the amendment was ratified in 1868, it had nothing to do with illegal immigration, a concept that did not exist back then. Instead, it focused on the reparation of rights to former slaves in the aftermath of the Civil War.

Since the country's founding, birthright citizenship had effectively reigned as a common-law practice. But in 1857, in the infamous Dred Scott v. Sandford decision, the US Supreme Court took away that privilege for people with African ancestry.

In the decision, the nation’s highest court ruled that regardless of whether they were free, African-Americans could never become US citizens. The legal argument was that African-Americans, having been considered inferior at the time the Constitution was drafted, were not part of the original community of citizens and were not subject to the protections that citizenship confers.

The citizenship clause was drafted to reverse that decision and grant the right of citizenship back to African-Americans.

In 1898, another Supreme Court case, United States v. Wong Kim Ark, reaffirmed the privilege of birthright citizenship.

Wong Kim Ark, who was born in San Francisco to noncitizen Chinese parents, sued for his right to citizenship after he was denied reentry back into the US. At that time lawmakers had passed the Chinese Exclusion Act, which limited Chinese immigration to the nation and made it impossible for legal immigrants to naturalize.

Still, since Wong was born in the country, the court ruled he was an automatic citizen.

“The idea was that birth in the free air and land of the United States was enough to establish them as a free citizen of the nation,” says David Abraham, a law professor at the University of Miami.

Critics of birthright citizenship focus on the phrase "subject to the jurisdiction thereof," which they interpret to mean that children of undocumented immigrants are subject to the jurisdiction of their parents’ home country and not the Constitution. They note that Wong's parents were legal immigrants and argue that citizenship should not be immediately extended to the children of people in the country illegally.

With Plyler v. Doe (1982), which focused on the rights of children to attend public school, the Supreme Court reinforced that the rights of citizenship should be conferred on the children of undocumented immigrants. But that decision is waved off by critics as specifically dealing with public school education and not with citizenship status.

Automatic citizenship at birth is more of an exception to the rule rather than a global norm, but legal experts say this is due to the cultural and historical development of the US. 

“The American version of birthright citizenship is the product of our very specific and intense history of a country that has grappled with slavery and has had a lot of immigration,” Professor Abraham says.