Indeed, when Gentiles, who do not have the law, do by nature what the law requires, they are a law to themselves, even though they do not have the law.
KJV
For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:
ASV
(for when Gentiles that have not the law do by nature the things of the law, these, not having the law, are the law unto themselves;