Recently, there has been a huge debate about revoking birthright citizenship from children born in the US to illegal alien immigrants. I read here that almost all left and right wings of the US political system will likely oppose this revoking birthright citizenship idea. Still, it's not clear to me that: is there anything to fundamentally prevent Trump's administration from revoking birthright citizenship, such as something in the US Constitution, or politicians just not helping Trump to do so because of the recent US political atmosphere? I will be very grateful if someone could explain this to me.
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.
Amendments amend the U.S. Constitution, so they are a part of the Constitution. Only further amendments can alter the language of other amendments, as seen by the passage of 18th Amendment and subsequent repeal by 21st Amendment. Most argue that, in order to revoke birthright citizenship, you would need to go through the process of amending the Constitution, which doesn't involve the President at all.
Some in the U.S. try to make the argument based on the phrase "subject to the jurisdiction thereof", and argue that people born in the United States to non-citizen parents aren't "subject to U.S. jurisdiction." Whether that's a valid legal argument is a bit out of scope for this site, but at least one question about it has been asked at Law.SE.
A President can revoke birthright citizenship, it's just that the revocation would likely be immediately challenged by courts, and potentially never enforced if it's found to be unconstitutional.
Technically, a US President has the authority to direct a federal official or agency to enforce the law in any way they choose through what are called executive orders. According to the American Bar Association:
Executive orders are issued by the President of the United States, acting in his capacity as head of the executive branch, directing a federal official or administrative agency to engage in a course of action or refrain from a course of action. They are enforceable to the extent that they represent a valid exercise of the President’s power (i.e. the action must be within the president’s constitutional authority).
However, as explained in that last line US Presidents cannot actually order the federal government to enforce their executive orders if they exceed the authority granted to the President by the constitution. Part of a President's responsibility as president is adhering to the US Constitution, and the Constitution makes it clear in the 14th amendment that any person born in the US must be given citizenship:
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.
So, if President Trump wrote an executive order that told the federal government not to give citizenship at birth, he may not have the ability to actually enforce it due to it potentially going against the Constitution. If he orders it but it is found unconstitutional, it could be struck down by courts and/or Congress could simply refuse to provide the funding necessary to carry out enforcement.
An alternative method to enforce this new citizenship law is through amending the Constitution itself to override the 14th amendment. However, such an amendment is not directly within a President's power: it would first have to be proposed by either a 2/3 majority of both houses of Congress or by Congress calling a convention of state legislatures, and then ratified by a 3/4 majority of state legislatures. This is not likely to happen anytime soon.
Addendum: Thanks to some comments by DrunkCynic, we have a court case that offers precedent to who the 14th amendment covers and how an attempt to reinterpret the citizen-by-birth section may be seen by courts.
The (very brief) background of this case is that for a time the US prohibited the immigration of Chinese laborers. A man named Wong Kim Ark was born in the US to Chinese nationals who were living in California at the time, and he lived most of his life in the US. Upon returning to the US from a trip to China he was denied permission to enter the US on the grounds that he was considered a Chinese immigrant rather than a US citizen.
He argued that he was in fact a US citizen, and the issue was resolved in the Supreme Court case United States v. Wong Kim Ark. According to this Cornell law summary of the 6-2 decision by the Supreme Court, it was ruled that he definitely was a US citizen and thus exempt from the prohibition on Chinese immigration:
A child born in the United States, of parents of Chinese descent, who, at the time of his birth, are subjects of the Emperor of China, but have a permanent domicil and residence in the United States, and are there carrying on business, and are not employed in any diplomatic or official capacity under the Emperor of China, becomes at the time of his birth a citizen of the United States, by virtue of the first clause of the Fourteenth Amendment of the Constitution...
In short, one could argue that this case upholds the idea that the 14th amendment applies to any person born in the US, even if born to non-US citizens. However, one could also argue that this case only applies to Wong Kim Ark's specific situation of being born to non-US citizens who were legal permanent residents at the time, and that the 14th amendment doesn't actually apply to children born to illegal immigrants.
So, any argument on whether or not a President can end birthright citizenship likely falls, at least in part, on the interpretation of this and related cases during any court challenge in the event that this ever happens.
The legal argument focuses on this part:
and subject to the jurisdiction thereof
Trump may take the approach of an executive order that declares people who did not enter the country legally are not subject to the jurisdiction of the US. That won't be applied retroactively to existing anchor babies, but it will exclude any future such occurrences.
Whether that argument will pass the supreme court or not, remains to be seen.
It should be noted that most European countries limit birthright citizenship only to children of legal immigrants or legal visitors. While their example doesn't directly apply to interpretation of the US constitution, it does show that this interpretation is not without long standing precedent. That may be a factor in a court judgment, as 'common law', or commonly accepted practices among democracies, is occasionally cited in legal arguments where the written law (or constitution) isn't entirely clear.
I found the argument put forth here to be quite compelling
Again, there are reports that the president may issue such an order. The problem as I see it is twofold. First, the legal landscape is not limited to the 14th Amendment. Congress has enacted a statute, Section 1401 of the immigration and naturalization laws (Title 8, U.S. Code). In pertinent part, it appears merely to codify in statutory law what the 14th Amendment says: included among U.S. citizens is any “person born in the United States, and subject to the jurisdiction thereof.” But that means the issue is not just what jurisdiction was understood to mean in 1868 when the 14th Amendment was adopted, but what it meant in 1952, when the statute defining U.S. citizenship was enacted (it has been amended several times since then).
Secondly, even assuming the meaning was the same, Congress’s codification of the 14th Amendment — which it did not need to do — is a strong expression of Congress’s intent to exercise its constitutional authority to set the terms of citizenship.
His point here (elaborated in the article) is that Congress has put forth a strong hint that they wanted birthright citizenship and that they wanted it as recently as 1952. It seems unlikely that any court is simply going to upend the apple cart and throw out an interpretation of a Constitutional amendment that Congress itself wrote into law just for good measure. As such, Congress would need to pass a law to change the meaning. Such a change is unlikely to happen.
Tim Pool did a segment that discussed various angles of this discussion that haven't been discussed here yet:
The short version (as has been discussed by other answers) is that he can end it, but the courts will almost certainly overturn it.
Some details that haven't been mentioned yet is that the meta discussions during the original drafting of the amendment specifically said that, of course the amendment wouldn't include children of diplomats or foreigners. This was, however, one comment amid what I can imagine is many. It may not represent the final interpretation of the language adopted by the Congress at the time.
So one point for the Constitution not supporting birthright citizenship. Which may not be an actual point depending on what further literature was generated during the Congress.
Subsequent case law, however, has set up ample legislative precedent for the idea that birthright citizenship excludes only those who are formally outside of the US jurisdiction -- i.e., diplomats. This case law has been discussed quite a bit in other answers.
So lots of points for numerous duly appointed judges and duly elected legislative bodies supporting birthright citizenship.
In the end, the only thing indicating that the Constitution doesn't grant birthright citizenship (so far as I've seen) is a comment by one of the drafters of the amendment. Everything else points the other direction.
In our constitutional republic, the President, and in fact any elected official, doesn't get to decide post-facto who is a citizen and who isn't. It isn't a difficult concept.
The text of the 14th Amendment says what it says, and the literal interpretation is what it is; and that literal interpretation has never been meaningfully questioned, until very recently.
If the President did, in fact, declare that a specific person's citizenship was null and void, perhaps via a tweet, even then, nothing would happen. Locally-elected law enforcement and district attorneys, who are responsible for the vast majority of arrests and prosecutions, would openly scoff at such an edict; but they don't have to report immigration offenses anyway. The courts, the state and local bureaucracies (such as the election office, the motor-vehicles department, public school districts and university systems, welfare offices) would continue to honor that unfortunate person's documents as normal. One's Social Security card, driver's license or photo ID, student ID, MediCare card, etc.
The private sector would continue to likewise process that person's documents, like normal. He or she could open a bank account, or interview and accept an offer of employment. Federal law enforcement, who arrest and prosecute people in federal court for a living, would continue to abide by the law; they have to. The only question is whether the secretive, black-helicopter types under the President's own formal authority would bend to the obvious, long-standing legal and procedural norms; and they very absolutely will, sooner or later.
The political and administrative bodies of government cannot take away citizenship. Even the courts, when rendering verdicts, are highly reluctant to treat citizens as non-citizens, under any circumstance -- including when one is guilty of treason. They can execute or incarcerate a citizen just as well as a foreigner, and they don't need to indulge the notion that a citizen is a non-citizen in order to perform their constitutional function.