...that mean they're 100% at fault? As an example look to the San Fran Zoo Tiger escape and killing. It seems that the city and media has laid all the blame on the killed man and his friends because he had trace amounts of marijuana and alcohol in his system. Is that even relevant to the case? I don't advocate drug use but didn't the tiger get out in large part because the walls were to low? Does this logic apply to prescription drugs too? Or is this just some BS to pass blame?

I'm not really referring to driving, in that case I feel the person has little defense.