You are so close, but... If a court document is needed to establish citizenship you are definitely not natural born. However, it is also true that if the legislature must make a statute to confirm citizenship you are equally NOT natural born. If one parent is foreign, as an example, the potential is there absent statute, that even if you were born in America your citizenship is a question. Obama is therefore NOT natural born, and Cruz is definitely NOT natural born.
This argument has gone on in numerous other threads since Cruz appeared on the scene. He is a natural born citizen as no court had to declare him a citizen as they do with naturalized citizens. Naturalized citizens do not have a mother or father who is an American citizen.
My grandson born in England was a natural born citizen the day he was born due to his father, my son, being an American Citizen. No court had to make him a citizen. He was issued an American passport the day he was born, plus he had British citizenship.
If he wanted to run for certain offices in England, he would have to give up his American citizenship. If he ran for certain offices in America, he would have to give up his British citizenship. Those offices require a single allegiance to the country.
Cruz had dual citizenship, US and Canadian; he has given up his Canadian citizenship so he has allegiance only to this country.
You will find out I am correct soon after Cruz files for President.