The most important invention of Hammurabi was the code of Hammurabi, a collection of laws.
I don't know how you can understand an "ingredient" of a code of law, but in some way this could be a specific law, so here is an example of a law from the code:
If an architect does not do his job well, and a house collapses, killing the son of the owner, the architect's son will be killed too.