Moral command versus Halacha

Hello, Your Honor,
I watched your interview on YouTube, in which the interviewer asked you what happens when there is a conflict between your morality and Halacha, and you answered that there is no clear answer, as sometimes you will follow morality and sometimes Halacha.
My question is, how can there be a moral command external to the law and not subject to it? What gives it its validity and binding force if not God?