The best arguments, by far, are against eligibility for Cruz.
The Pennsylvania judge mostly just quoted law review articles, especially the one from Harvard by the former and former (acting) Solicitors General (conveniently produced just in time for this election season). The Pennsylvania opinion has little or no analysis of original sources, and relies heavily on the analysis and arguments in secondary sources such as the Harvard article, without any recognition of the problems, including potential mis-use of original sources, in the secondary sources.
The Harvard article in particular has many problems. One of the big ones is that the Harvard article, after stating (correctly) that English common law is an important source for interpreting the U.S. Constitution, then completely ignores English common law and just uses English statutes as if they were the English common law, without even mentioning, let alone justifying, this sleight-of-hand.
The New Jersey judge appears to have made a more serious effort (or maybe the Cruz legal team's briefs, where the analysis probably originated, were better by that time). The New Jersey opinion uses a lot of text attempting to justify the concept that English statutes are part of the English law for purposes of interpreting the "natural born" requirement in Article II.
A major problem with this position is that the only support for including English statutes as a part of the common law comes from cases interpreting issues of state law. The states, which were basically created instantly from pre-existing colonies upon independence, naturally continued to follow the major laws of England where applicable, some by explicit legislation receiving the English law into the law of the state, and (apparently) some by judicial decision. Federal law, and federal Constitutional law in particular, is a different matter. There is no citation in the New Jersey opinion of any case that uses English statutes as a part of the English common law for purposes of interpreting the U.S. Constitution.
In addition to relying on weak support (only cases based on state law issues), the New Jersey opinion does not deal with some of the stronger arguments that the "natural born citizen" clause did not and does not incorporate the English statutes in force at the time of drafting and ratification.
For example, if the Founders created the "natural born" requirement with the understanding or intention to incorporate the statutory laws of England, then why, in the notes of the committee discussions of the drafting of the Naturalization Act of 1790, did one of the committee members state that "The case of the children of American parents born abroad ought to be provided for, as was done in the case of English parents, in the 12th year of William III." If the English statutes were already incorporated, why was Congress in 1790 drafting a law specifically in order to provide for what was already provided for in one of the supposedly incorporated English statutes?
The best arguments, by far, are against eligibility for Cruz.
So what? The significance of what he did was that he granted standing to the plantiff, he stated the facts, applied the law and made a decision. His decision included that Mr. Cruz was eligible for the Office of President, and that Cruz was a Citizen by Birth and that was identical to the term Natural Born Citizen.
More significant, the Pennsylvania Supreme Court affirmed the decision and did so Per Curiam, which means that they did not issued a written decision. This occurs most often when the court rules unanimously and when the issue is not controversial (from a legal standpoint).
An appeal has already been filed, so fasten your seatbelt, we're in for a bumpy ride.
My views of this dispute can be summarized from two perspectives:
The first view can be seen from the Constitution and the legal history of this subject. The best discussion that I have found and one that I agree on most points has been written my Michael Ramsey (see link below). I don’t think that the call is as close as he presents, but he does give a good review of both points of view and he provides good references. I believe that the founders were following the example of both English common law and statute history to define the classes of citizenship that was clearly understood by educated contemporaries. I think that the current law as reflected in USC 8, Section 1401 is exactly what the founders intended the Congress to do and their legislative actions are well within that powers. As Pellegrini has said, Citizen at birth and Natural Born Citizen have the same meaning and therefore Mr. Cruz is eligible for the Office of President.
My second view is a prediction on what the courts will do. We now have the first two decisions that directly address the issue of Presidential eligibility. We no longer need to rely on articles, or worse, some convoluted and incorrectly reading of some unrelated SCOTUS opinion. I believe that courts will agree with these two decisions and this approach will become the consensus in the courts. The reasons are not just legal, they are certainly shaped by politics. Today’s courts are never going to say that descent of citizenship can occur from the father to his children, but not from the mother. Since the courts have generally accepted that the 14th Amendment decided that all persons born on U.S. soil (excepting those of diplomats) are natural born citizens, the courts are never going to say that children of American citizens born abroad cannot be natural born citizens. While some rogue judge or court may say something different, in the end the Pennsylvania and New Jersey cases will prevail in some form.
I doubt that this dispute will make it to the Supreme Court, but it should. More likely, the Court will let a lower court decision stand and that will be the end of it. The courts did not bail out those who didn’t want Obama elected in 2008 and they won’t bail out the voters this year either.
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2712485