Laws

Let's take a look at laws for a moment. In recent times most countries have started shying away from religious rational for laws and are looking at pure secular reasoning for writing laws. The problem is how is it possible for secular reasoning to be the basis of a law?
Let's take an extreme example that should make the problem apparent. It is illegal to kill someone.
Easy enough right? Killing bad ergo illegal to kill. By why is killing bad? Well, we could think of it like I do not want to be killed. It is reasonable to assume that everyone would not want to be killed. Therefore, it is illegal to kill anyone. The problem is the basis for this law is a desire.
Does anyone see any problems with basing laws on desire?



Also discovered Bad Translator and had a little fun.
Original text:
"It is illegal to kill someone. Easy enough right? Killing bad ergo illegal to kill. By why is killing bad? Well, we could think of it like I do not want to be killed."
...54 translations later we get:
"And so easy and can be killed or not? Ham, evil Dead 2, 5, Regardless of the murder."