The whole birthright citizenship thing is rather interesting. Anybody who says it's a clear cut issue is bonkers. The whole "subject to the jurisdiction" thing isn't cut and dried. The way the 14th Amendment is written doesn't address parentage. It's basically saying, "is the person born here subject to the jurisdiction of the USA."
Well, aliens, legal or otherwise, are not subject to the same jurisdiction as an ordinary citizen (you see it gets kinda circular here). For one thing, they can't be drafted and can't serve in the military. Illegal aliens can be expelled at will. Legal aliens have no "right" to be here and can be expelled easily. Since typically they are citizens of other countries (assuming both parents were citizens of a foreign country), they could be convicted of treason in that country, serve in that country's government, and even be forced to serve in the military.
Was "subject to the jurisdiction" only intended for diplomats? I don't think so. After all, diplomats are still subject to jurisdiction, albeit very limited jurisdiction in some cases. At the time it was widely recognized that children of diplomats weren't citizens anyway, so there wasn't much need to address that issue.
Around that time the civil rights act that was passed declared, "All persons born in the United States and
not subject to any foreign power, excluding Indians not taxed, are declared to be citizens of the United States." (emphasis added) That provides some context about the intent of the 14th Amendment. Furthermore, when we think about the intent, did the states passing it envision that the child of a husband and wife spy team being a citizen? If an army invaded the USA, would children born to the invaders while on American soil be citizens?
According to
this site, Chairman of the House Judiciary Committee (39th Congress), James F. Wilson of Iowa, added on March 1, 1866: “We must depend on the general law relating to subjects and citizens recognized by all nations for a definition, and that must lead us to the conclusion that every person born in the United States is a natural-born citizen of such States,
except that of children born on our soil to temporary sojourners or representatives of foreign Governments.”
Apparently Senator Trumbull at that time declared, "The provision is, that ‘all persons born in the United States, and subject to the jurisdiction thereof, are citizens.’ That means ‘subject to the complete jurisdiction thereof.’ What do we mean by ‘complete jurisdiction thereof?’
Not owing allegiance to anybody else. That is what it means." (ibid)
To me it makes a lot more sense that the intention was not to include legal or illegal aliens. Would Americans have really intended to create a situation where citizens of another country could pop across the border for a day, have a baby, return back to their home country, then send that kid back 35 years later so he could run for the president of the United States? Seriously. We prohibit naturalized citizens from running, but we wouldn't want to prohibit the aforementioned scenario?
That subsequent court rulings and decisions have muddied the waters is not in doubt. It's not crystal clear. Personally, I think the right way to handle it is to create an amendment to the amendment clearing it up once and for all. I, for one, don't think that exiting the womb on American soil should grant someone citizenship. There are plenty of other countries that feel the same way.