Donald Trump is talking about "anchor babies," and now Jeb Bush is doing it too (video here) as the Trump effect pushes mainstream Republicans into adopting the discourse of anti-immigrant activists. Hillary Clinton's campaign smells an opportunity to slam Bush for adopting Trump's rhetoric, while more and more Republicans are questioning the 14th Amendment's guarantee of birthright citizenship.

Se llaman "bebés," "niños," o "ciudadanos." https://t.co/ofxEG6Za00 — Hillary Clinton (@HillaryClinton) August 20, 2015

And yet lurking behind the Latino politics issue is the largely separate, though legally related, phenomenon of "birth tourism" primarily related to Chinese citizens rather than would-be migrants from Latin America. Pro–immigration reform Republicans are seeking to highlight this topic as a means of showing support for immigration restriction without alienating Latino voters — but as the Clinton campaign's glee shows, that's a narrow and difficult plank to walk.

What is an "anchor baby"?

This is not a legal term, nor one that anyone would non-ironically self-identify with, nor one that is used in immigrant communities. But the idea, broadly speaking, is that because a child born on US soil is automatically a United States citizen, adult non-citizens are having US-born children in order to manipulate the immigration system. A person who came to the United States illegally before giving birth — or who gave birth while here on a temporary visa — might be less likely to be deported later on because her child is a US citizen.

When the US-born baby grows up, she could even deploy her status as a US citizen to petition for legal immigration papers for her parents on family unification grounds.

The idea is that the baby exists as an "anchor" to keep the family in America.

Why is the term considered offensive?

People find the term objectionable on two grounds.

One is that it seems to imply, contrary to the law and the Constitution, a two-tiered scale of citizenship in which some people are real US citizens and others are mere grown-up anchor babies.

The other is that while it is unquestionably true that babies are born to both unauthorized migrants and to temporary visa holders, the implication that such babies are typically the product of a cynical, decades-long effort to manipulate the immigration system rather than the normal bonds of familial affection is a little far-fetched and insulting.

What is birthright citizenship, and where does it come from?

The 14th Amendment to the US Constitution states, "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."

This was, at the time, primarily intended to nullify the Supreme Court's infamous 1857 ruling in Dred Scott v. Sandford, which ruled that no African American could become a citizen regardless of birth.

In the mid-19th century there were no legal restrictions on immigration to the United States, so there was no particular legal question about the citizenship status of the children of people who came to the US without legal authorization to permanently reside here. Then Chinese Exclusion Acts were passed in the 1880s, and in 1894 a man named Wong Kim Ark, who'd been born in San Francisco, came back to the US after a visit to China. But immigration officials wouldn't let him in. He protested that he was a citizen; the federal government used the case to lay out the position that (in the words of historian Erika Lee) "American-born Chinese could not be considered citizens if their parents were not, and could never become, naturalized citizens."

The case made its way to the Supreme Court, where the justices ruled 6-2 in favor of Wong, stating that "the right of citizenship ... is incident to birth in the country."

As immigration law and immigrant flows have changed over time, this legal principle has carried the day. The plainest reading of the 14th Amendment is that if you are born in the United States you are a United States citizen, and the immigration status of your parents is not relevant.

Does having a baby on US soil really protect you from deportation?

No. It is true that given the bad publicity involved, the parent of a US citizen is less likely to be deported than a childless unauthorized migrant would be. But 200,000 parents of US citizens were deported from July 2010 to September 2012.

Birthright citizenship is a principle of constitutional law, but leniency for the parents of US citizens is more or less a discretionary aspect of immigration enforcement.

Since the resources available for apprehending and deporting unauthorized migrants have varied over time and have always been inadequate to the task of deporting millions of people, the ins and outs of enforcement practice have varied considerably and will continue to vary.

How many US citizens have unauthorized parents?

As of 2010, 4.5 million US citizens under the age of 18 had at least one parent who was an unauthorized immigrant. (It's entirely possible that the number has changed as the unauthorized immigrant population has gotten more settled over the past few years.)

That likely includes an awful lot of American school kids. As of 2012, 6.9 percent of all students enrolled in kindergarten through 12th grade in the US had at least one unauthorized immigrant parent; 5.5 percent of all K-12 students were US citizens with at least one unauthorized immigrant parent. That's one out of every 18 school-age US citizens.

Is birthright citizenship common internationally?

There is, of course, a great deal of international variation in citizenship law. But broadly speaking, countries in the Western Hemisphere tend to emphasize place of birth (jus solis), whereas countries in the Old World have traditionally emphasized ancestry (jus sanguis).

Part of the difference is that many Old World countries regard themselves as, in part, custodians of an ethnic or national heritage that transcends geography.

For example:

Israel is a Jewish state and extends to Jewish people around the world the right to "return" to Israel and become an Israeli citizen.

Finland is a land of Finnish people and extends a similar right to Finnish-speaking ethnic Finns residing in Russia.

A 2010 Hungarian law grants Hungarian citizenship to hundreds of thousands of ethnic Magyars living on the territory of the pre–World War I kingdom of Hungary (primarily in Slovakia).

Ethnic Greeks have lived outside the current boundaries of the Hellenic Republic for thousands of years, and they can become Greek citizens by volunteering to serve in the Greek armed forces.

Rules along these lines are common in Europe and often shift in nature. Throughout its existence as a country, West Germany offered citizenship to ethnically German residents of Eastern Bloc countries on fairly generous terms — a legacy of post–World War II boundary adjustments and of the extreme practical difficulty of emigrating from communist states. Since 1990, these rules have been repeatedly tightened to require proof of German language skills and cultural affinity for Germany due to a perception that citizenship privileges were being abused by residents of poor post-communist countries who weren't "really" German in relevant ways.

At the same time, many immigrant-heavy European states — including France, Germany, and Sweden — have changed their laws in recent years to incorporate more elements of the jus soli approach.

What's this about birth tourism?

"Anchor baby" rhetoric has, historically, referred to children born to long-term unauthorized residents of the United States, typically immigrants from Mexico or elsewhere in Latin America. That rhetoric is toxic in the Latino community, where obtaining legal status and a path to citizenship for such long-term residents of the United States is a key political demand.

Republicans who favor immigration reform — such as Jeb Bush and Marco Rubio — have been trying lately to shift the conversation to a different phenomenon referred to as "birth tourism," in which pregnant women (typically Chinese) enter the country legally on short-term tourist visas and give birth to children on US soil.

As best we can tell, the "birth tourism" industry caters overwhelmingly to Chinese parents-to-be, who can get tourist visas to stay in the US for up to six months. The Chinese government says 10,000 babies were born in the US to Chinese tourist parents in 2012; more recent, unofficial estimates are higher. (There's a very thorough recent feature about this from Benjamin Carlson of Rolling Stone.)

This is definitely an abuse of the tourist visa, and the United States isn't turning a blind eye to this. Embassy officials and Customs and Border Protection agents have started questioning Chinese women who look like they could be pregnant. There are also stateside crackdowns on the "hotels" where birth tourists stay. Since lying to them is illegal, parents-to-be who lie through the interview are breaking the law. But fundamentally, they are holding legal visas and therefore are in the United States legally.

In general, birth tourists do not appear to be interested in immigrating to the United States. They typically return to China with their babies. What they are doing is obtaining a future right for their child to move to the United States — a valuable commodity in general, and a potentially useful hedge against hypothetical political instability in China.

How could birthright citizenship be reformed?

There are basically three approaches:

The Supreme Court (or some future set of justices) could rule that people who are in the United States without permission are not "subject to the jurisdiction thereof" and that therefore, their children are not US citizens within the meaning of the 14th Amendment. This somewhat odd reading of the text would be bolstered by the observation that neither the authors of the amendment nor the justices in the Wong Kim Ark case had unauthorized migration in mind. Sen. David Vitter and Rep. Steve King have bills in Congress that purport to "clarify" the scope of birthright citizenship and take it away from the children of unauthorized migrants. This is fine politics as far as it goes, but is not really how the US legal system works. Last, a 28th Amendment to the Constitution could be passed and ratified in order to alter US citizenship law. Amending the Constitution is, however, a difficult political lift.

One irony of the situation is that while the broadest political consensus seems to exist for a crackdown on birth tourism, it's legally the hardest to address. The Supreme Court could rule that unauthorized immigrants aren't subject to the jurisdiction of the United States, but birth tourists aren't in the United States illegally. A constitutional amendment could specify a minimum period of parental residency (this is how European countries with restricted jus solis do it), but constitutional amendments are difficult to pass.

Alternatively, the US could pass a blanket ban on pregnant women obtaining temporary visas to enter the United States. But this could have negative consequences for international commerce, and would invite retaliation by foreign governments. A narrow birth tourism fix, moreover, would not address the political problem that Bush and Rubio are faced with, namely a desire to signal sympathy with Trump's constituency without alienating Latino voters.

What's a counterintuitive pro-immigration argument against birthright citizenship?

Fans of Slatepitching will enjoy Will Wilkinson's argument on this score.

His point is that ending birthright citizenship would open the door, politically speaking, to a considerably more generous approach to future temporary guest workers. Such workers would come to the United States for a year or five, pay taxes, and then return home without ever becoming eligible for most of the country's expensive social welfare programs. They would be employed (by definition) rather than retired or living on welfare, and if entry were restricted to adults they wouldn't be a cost center for local school systems.

But to make it work you have to be able to kick out the "guests," which means no "anchor babies," which means no birthright citizenship.

It's an interesting argument, and if you want to agree with current trends in Republican Party thinking without personally associating yourself with demagoguery it's probably the best you are going to do. But it has a bunch of flaws: