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.

A Healthcare Public Option is Pure Pablum

There are several ways to improve the healthcare market to lower costs, but they involve freeing doctors and insurance companies from burdensome regulation instead of creating a socialist “public option”. Universal healthcare would be an affront to human liberty and the value of human life.