It's called a Penal Code. Easily Googled on the Internets.....
Very well.
Laws create structure and stability within a group. You are correct Laws don't stop criminals, but just as in pre-recorded history, if you broke the rules binding a tribe together you were ostrcized from that group and no longer had its protection or resources.
While criminals will create problems due to not following Law, most people in the group will thus creating a stable environment for the group to flourish. This is ofcourse assuming the laws are just and freely accepted by all.
Then did you actually mean 'Penal code' when you said Laws, anywhere in there? Because it's the penal code I have issue with, the actual, codified behavior->punishment list which, as I said, allows things which it should not, simply because there's no rule against it, and punishes behavior it should not, simply because there is.