You're just mixing the definitions.

The law that's being discussed is law in the sense of the written part of the social contract, or whichever way that's defined. In any case, it's merely a matter of writing down and establishing formally the enforcement of social norms.

What Leibneiz would be referring to is law in the sense of a law of nature, i.e., a pattern that has been detected in nature itself, and could be considered objective. (in the sense that rocks fall down whether you think that it's appropriate or not.)

In fact, making natural laws into written laws is ridiculous, especially when you're making up fake laws. Saying that it's illegal for charge to pass from high-potential locales to low-potential locales is meaningless, and silly. (So is making Pi equal 3.)