The limitations would be how much evidence was available and the truthfulness of the witnesses. The Code dealt with violations of the law. The law specified punishments based on who you were...slave or master, etc..
I would say language diffusion
Answer:
I would say what was most important would be the adoption of agriculture. Humans no longer had to move around and spend their days solely focusing on finding food. Being able to settle down and make one's own food allowed humans to have free time, and create hierarchies and languages and art, creating societies and civilization.