Wow! I hope that Cruz is correct. That means that every illegal immigrant that comes to US and has a baby here isn't a US citizen.

Some legal scholars, that are Constitutional lawyers, define a natural birth, as being one that is born in US territory. If not, then you become a naturalized citizen of a foreign birth. If that interpretation is correct, then Ted Cruz can't run for the Presidency, because he was born in Canada. Once he and his parents moved to the US then he became a naturalized citizen by his mothers birth rights in this country (US). However, legal scholars don't substitute for a SCOTUS decision, so it will eventually be decided in 2016, if it is necessary, by SCOTUS. The possibility exists that Ted Cruz may not be the standard bearer of the Republican Party. In his legal challenge to his natural born citizenship it doesn't become mute, because he is not picked, but it may not be important to have a SCOTUS decision in time for the Republican Convention. The issue should be determined immediately by SCOTUS, show that issue is decided, which could change how the Republican Convention does elect their standard bearer. This decision, if it comes, would only be fair to the people who are candidates for the Presidency from the RP, but also, for the voters who may chose to vote for Ted Cruz, or someone else in the RP primaries. It would be a shame if Ted Cruz becomes the standard bearer for the RP, and he is then disqualified before the November 2016 election. If no decision is forthcoming and he is elected, then an impeachment hearing, and vote to remove him would be necessary, in Congress. Let's hope, that it never reaches this point in time, for our nation to remove a sitting President, for Constitutional qualifications.

What about Canadian Values, Ted?
Technically according to the Constitution Ted Cruz was legally born a Cuban/Canadian because of his father. Mothers are not considered when determining "Natural-Born" Citizenship.

Extending citizenship to non-citizens through birth based solely upon locality is nothing more than mere municipal law that has no extra-territorial effect as proven from the English practice of it. On the other hand, citizenship by descent through the FATHER is natural law and is recognized by all nations (what nation doesn’t recognize citizenship of children born wherever to their own citizens?). Thus, a natural-born citizen is one whose citizenship is recognized by law of nations rather than mere local recognition.

Chairman of the House Judiciary Committee, James F. Wilson of Iowa, confirmed this in 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.”*

When a child inherits the citizenship of their FATHER, they become a natural-born citizen of the nation their FATHER belongs regardless of where they might be born. It should be pointed out that citizenship through descent of the FATHER was recognized by U.S. Naturalization law whereby children became citizens themselves as soon as their FATHER had become a naturalized citizen, or were born in another country to a citizen FATHER.

Yes, birth is prima facie evidence of citizenship, but only the citizenship of the nation the father is a member.

* Temporary sojourners like transient aliens were a description applied to aliens other than resident aliens. The difference being temporary aliens were here for temporary purposes, such as work, travel, visitation or school, who had no desire to become citizens or was prevented from becoming citizens by law. Resident aliens were those who desired to become citizens and had renounced their prior allegiances and had taken the legal steps to become citizens or reside within some state per state law.

UPDATE: In regards to questions about the citizenship of the mother: Mothers citizenship rarely ever influenced the citizenship of their children except in certain situations such as the father dying before the child was born or when the identity of the father was unknown.

Yup, why bother with lawyers specialized in citizenship law and supreme court judges when we have Luigi from the internet.

Luigi demonstrates his lack of knowledge about the constitution in his second sentence. The constitution never defines what natural born citizen means. Thus, the problem. At least trump is consistent, in that he brings up the birther notion all the damn time.