SCOTT SIMON, HOST:
This week, President Trump put an idea back into the national conversation that he's been talking about for years. Here he is in 2016.
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PRESIDENT DONALD TRUMP: No. 1, the 14th Amendment is very questionable as to whether or not somebody can come over, have a baby and, immediately, that baby is a citizen, OK?
SIMON: And here's the president in an interview with Axios, again talking about revoking birthright citizenship.
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TRUMP: Now how ridiculous, we're the only country in the world where a person comes in, has a baby and the baby is essentially a citizen of the United States for 85 years with all of those benefits. It's ridiculous.
SIMON: Context is important here, and we asked two historians to remind us how the 14th Amendment to the Constitution came to be. Here's Nell Irvin Painter, professor emerita at Princeton University, on why it was written back in 1868.
NELL IRVIN PAINTER: It was enacted for the recently free people in the American South. And it was to protect their citizenship rights and reverse the Dred Scott decision of 1857.
SIMON: That infamous decision made by the Supreme Court ruled that Dred Scott, an enslaved man who had sued for his freedom and who resided in a free state and territory, was not entitled to that freedom. The decision said, in essence, that African-Americans could not be U.S. citizens. That ruling became infamous. The 14th Amendment overturned it. There was little opposition, except, of course, in former Confederate states.
PAINTER: Remember, the United States didn't have limits on immigration. This was an economy that badly needed labor. But the mobilization of anti-immigrant sentiment of the sort that would appear in the early 20th centuries and peak in the 1920s - that sort of thing didn't appear.
SIMON: The first section of the amendment reads, (reading) 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. But in practice, it didn't mean all persons. Here's Erika Lee, professor of history at the University of Minnesota.
ERIKA LEE: There has been such a gap between what those words say and what they have meant in the lives of everyday Americans, especially Americans who are minorities and people of color.
And so there's a case that occurs in the late 19th century that is a perfect example of this gap between ideals and reality. And that involves a Chinese American citizen by the name of Wong Kim Ark. So this is a guy who was born in the United States of parents who are of Chinese descent.
But in the 1890s the U.S. government is looking for a test case to really determine whether Chinese people, whether born in the United States or not, can really be considered American citizens. And so they focus on Wong Kim Ark when he tries to re-enter the country in 1894, and they actually deny him readmission.
So Wong Kim Ark fights back, and it goes all the way to the Supreme Court. The majority rules that the language of the amendment is very clear and that all persons born in the United States are citizens thereof and that citizenship is not something that is descended or inherited, but that it's about place and territory.
SIMON: However, Wong Kim Ark didn't even tell his family that he'd won his case, and his citizenship continued to be questioned every time he went in and out of the United States. He retired, disillusioned in China, and never returned to the United States. His case, however, has remained fundamental.
LEE: This case hasn't been overturned. But we haven't seen a mainstream push for this kind of action until now.
PAINTER: It really is the bedrock of what makes the United States a special country. Not every country has birthright citizenship, but in the United States if you're born or naturalized, no matter who you are, no matter what your blood is, you can exercise your citizenship right. That is of fundamental importance in a multiracial, multicultural democracy.
SIMON: Most constitutional scholars and legal experts and even many Republican officeholders agree that President Trump cannot undo birthright citizenship with an executive order. The 14th Amendment is in the Constitution of the United States.
(SOUNDBITE OF BRAD MEHLDAU'S "BLACKBIRD") Transcript provided by NPR, Copyright NPR.