How do we determine Natural Law?

I often think back to a small clip I saw years ago of the late Justice Antonin Scalia explaining his view on Natural Law and why we should leave decisions to democratic institutions and not courts.

Order is so important

Life, liberty, and property do not exist because men have made laws. On the contrary, it was the fact that life, liberty, and property existed beforehand that caused men to make laws in the first place.