Jennifer posted a link to an excellent treatise in my opinion. Plus she has her own slant that is very enlightening.
"In a truly honest society of responsible adults, there would be no need of laws. I don’t refrain from killing people because it is against the law. I don’t go around killing people because that would be wrong. I don’t need the force of law to tell me that another human being has a right to life. On the other side of that, if someone decided that they wanted to kill me, I would gain nothing by yelling, “But that’s illegal!”
Click the above and be sure to click the link she posts as well.