If you're stupid enough to use it knowing the effects of what it can do, and suggesting you're not forced; you should not be put in jail, rather a padded room.
I'm not aware of any real adverse effects, however if you consider the high itself a bad effect I can't really speak. It's not addictive in the way other drugs are. The only real addiction that it could possibly have is how people like and want more of good things.
In fact, nobody has overdosed on it. The effects it has may have had a part in some deaths however. Although there probably aren't many of these, most people who smoke it (as far as I know) don't do anything really dangerous while under its influence.
You can also get rid of the effects the smoke has on your lungs by vaporizing it.
This kinda reminds me of the "Anti-Drug" month we had in school. Every few days it'd be a new drug, and I got points marked off for describing some of the benefits of marijuana. I asked her what her reasoning was for marking the question wrong, and all she would say is that "I'm an adult and I know more than you do, don't question me."