The saying "buyer beware" never rings more true than when a purchase is being made on the black market. Especially when the market in question is that of illegal narcotics.
Of course, both parties seek to benefit from any free exchange, but drug transactions carry significant risks. The dealer could be arrested, or the purchaser could have an adverse reaction. Now a further risk has been added to the mix: the threat of being sued.
A Canadian woman who spent 11 days in a coma recently succeeded  in suing her drug dealer. Apparently the dealer knew that the drug was "highly addictive and dangerous" but sold it to her anyway, in order to make money. (Really? I'm shocked...) This made him negligent, and liable for damages.
In fact, the only reason why the case was successful was that the dealer refused to name the person in the distribution chain above him, thus moving the judge to reject his defence. The decision probably won't be too hard to appeal.
In any case, the person who has really been "negligent" here is surely the consumer, indulging in self-abuse via the consumption of drugs without regard to the harm that they can inflict. She should not have had recourse to sue.
That she did is symptomatic of the ever-growing need to seek restitution from others for our own mistakes. We seem to be moving to a culture of blame rather than of individual responsibility.
People need to be made aware that sometimes, if not almost all the time, the buck stops with them.