THE EXTANT LAWS would be understood only of such as were on record but not in operation, of laws as

A text: THE EXTANT LAWS would be understood only of such as were on record but not in operation, of laws as documents and not as forces.

I get a handle on the meaning, but the grammar is beyond my explanation.

eg Such advice as he was given (= it was not very much) has proved almost worthless.
eg He is not half such a fool as they think.
eg there's no such thing as free lunch.

I understand all these sentences, but in the text why is OF used?