If we coulden't lie then everyone would be right no one would be wrong.
The problem would start with religon...
Every one will think there way of life to be the "holy" path but the problem is no one knows what is the right oneis or if its even been found yet untill we die.
Then it will be who killed so-n-so and if we cant lie "I didn't do it" will be enof and no more investagating will be done on that person.
Mabe hes/shes got a split personaty and cant remember so when hes/shes asked they wont know for certen.
Last but not least will we still have free will anymore, I say no for we will be forced by an unknow force to tell the truth forever no mater what to witch can drive a person mad.
If you don't blieve me watch LierLier and say you don't HAHA!