What was the roman political system devised by augustus as a disguised monarchy with the "first man" as emperor?

The correct answer is principate

Augustus considered the Senate where he had served as leading member (princeps senatus)  as a body with important functions. This included managing foreign affairs and judicial matters. Its members filled the highest offices and its decrees were binding.

the answer to your question is a because laws act as guidelines as to what is accepted in society. without it there would be conflicts between social groups and communities. it serves as a norm of conduct for citizens.