This isn’t about the definition of “natural born citizen” but it comes out of the principles behind that debate.
Common law refers to law and the corresponding legal system developed through decisions of courts and similar tribunals (called case law), rather than through legislative statutes or executive action. [Wikipedia]
Ignoring all that’s come before, I launch into my personal thoughts about these terms.
One intuitively feels that there are some universal truths, that we should care for our families, for example. But we also know that human nature has a negative side. While I might agree that there are some universally valid principles, I am skeptical in principle that we can tell the differences between them and simple prejudice. I certainly don’t trust in everybody left to their own devices doing the “right thing”.
Because people have difficulty separating their own prejudices from universal principles (thinking every view they hold should be universal) arguments based on natural law tend to be self serving arguments.
Common law, as I see it, is more pragmatic. It comes out of the forge of debate and is tested over time. Common law may be rooted in some understanding of natural law, but it is better “vetted”.
When I come across an argument about citizenship that is based on natural law, I expect to find an undercurrent of racism and prejudice. (When I say “racism” I don’t necessarily mean white racism against blacks, but rather any generalized distrust or stereotyping of any group that is racially, ethnically or nationally different.) Whether it was the Irish, the Chinese, the Puerto Ricans, the Mexicans, the Jews or the Africans, Americans have a sorry history when it comes to color-blindness in the community. The Chinese Exclusion Act and slavery are two examples from history, and it wasn’t so long ago that I saw a sign in a local restaurant: “we don’t serve Iranians”.
Because I don’t trust human nature, I don’t trust natural law. Perhaps the courts do a little better.