Consider this story:
One evening, Bob walks trough the park and witnesses how a man apparently sells drugs to a group of minors. As he approaches, the man runs away, but Bob catches up on the minors. He gives them a sermon about drug abuse they won't forget for a while. At the end, they more or less voluntarily hand him over their merchandise. As he walks away, Bob disposes off the drugs and considers the issue resolved.
However, the next day, one of the minors reconsiders the story and wants to sue Bob for destroying his property. He requests Bob to pay $200 or the equivalent in narcotics.
Does Bob have to fear anything? Could he be liable? To keep it simple, we can assume that the drug in question is illegal to sell, use or own in any quantity.