I'm really disappointed in the quality of the replies to this. I would hope that HN would be just a little more fact based, instead of having people willing to argue over trivially falsifiable claims.

The fact is, booby traps which cause bodily injury (including paintball, very easily, without protective equipment) are definitively illegal in most jurisdictions. This is the truth whether you spend 5 seconds or 5 hours googling.

Do better, all of you.