They argued that Wong was not a citizen at all. In their appellant brief they wrote,
"The question presented by this appeal may be thus stated: Is a person born within the United States of alien parents domiciled therein a citizen thereof by the fact of his birth? The appellant maintains the negative, and in that behalf assigns as error the ruling of the district court that the respondent is a natural-born citizen."
But Judge Morrow of Northern District of California never ruled that Wong Kim Ark was a natural-born citizen. He like Justice Gray only said that Wong was a citizen by his birth in California. The US Government assumed that in declaring him a citizen by birth in the United States, the court was declaring him to be natural born.
Later in the same brief the US Government wrote,
"For the most persuasive reasons we have refused citizenship to Chinese subjects; and yet, as to their offspring, who are just as obnoxious, and to whom the same reasons for exclusion apply with equal force, we are told that we must accept them as fellow-citizens, and that, too, because of the mere accident of birth. There certainly should be some honor and dignity in American citizenship that would be sacred from the foul and corrupting taint of a debasing alienage. Are Chinese children born in this country to share with the descendants of the patriots of the American Revolution the exalted qualification of being eligible to the Presidency in recognition of the importance and dignity of citizenship by birth?"
In his dissenting opinion, Chief Justice Fuller wrote,
"Considering the circumstances surrounding the framing of the Constitution, I submit that it is unreasonable to conclude that "natural-born citizen" applied to everybody born within the geographical tract known as the United States, irrespective of circumstances, and that the children of foreigners, happening to be born to them while passing through the country, whether of royal parentage or not, or whether of the Mongolian, Malay or other race, were eligible to the Presidency, while children of our citizens, born abroad, were not."
Two prominent lawyers at the time of the Wong Kim Ark decision also expressed their opinions on the case.
William Dameron Guthrie, 1898
"This decision [Elk v. Wilkins] left in uncertainty the legal status of all others born in the United States of alien parentage. Was their citizenship to be determined by the common-law principle of locality of birth, or was the rule of the civil law as to the allegiance of the parents to control? This question was not settled until a few weeks ago, thirty years after the amendment adopted, thus showing how slowly constitutional law develops in the life of a nation. The common law rule has been finally affirmed by the Supreme Court in the recent case of the United States v Wong Kim Ark. The Supreme Court held that a child born in this country of Chinese parents domiciled here is a citizen of the United States by virtue of the locality of his birth. The whole subject is discussed at length in the opinions of this case. The effect of this decision is to make citizens of the United States by virtue of the Fourteenth Amendment all persons born in United States of alien parents permanently domiciled and residing here, except the children of the diplomatic representatives of foreign powers; and, therefore, a male child born here of alien Chinese subjects is now eligible to the office of President, although his parents could not be naturalized under our laws." 1898
And Alexander Porter Morse, 1903
Under decision of the Supreme Court of the United States, a child of domiciled Chinese parents, if born in the United States, would seem to be eligible to the office of President and to all the privileges of the Constitution, while the child of American parents and grandparents, born on shipboard or in foreign territory in travel or transit, might be excluded from similar rights and privileges.
A natural-born citizen has been defined as one whose citizenship is established by the jurisdiction which the United States already has over the parents of the child, not what is thereafter acquired by choice of residence in this country.
The conclusion is, that the child of citizens of the United States, wherever born, is 'a natural-born citizen of the United States,' and, as such, if possessed of the other qualifications, would be eligible for the office of President of the United States.
I think it is clear that the thinking at the time was that if you were not naturalized than you were natural born regardless of the status of the parents.
The matter remains undecided at the SCOTUS level, the closest thing being the opinion by Story writing for a unanimous court in Shanks v. Dupont Story's opinion would not be helpful to Cruz, Rubio, Jindal, or, for that matter, Santorum. Cruz will not get the free pass when attacked on this issue that the present occupant of the Oval Office got.