In what specific case do you refer to, because I knew about a law back then If you were a child of a USC then you were automatically granted citizenship. My father is 68 years old born in Mexico but his grandfather was a natural born USC so therefore his father , also born in Mexico was automatically granted his citizenship in the US. Can this apply to my father as well?
Derived Citizenship is a complex calculation and made even more complex because the laws changed every so often. So, I would suggest you seek private consultation if you so choose. Best Wishes! -Lalita