First, you say that this scenario appears old. Is it just an outdated exercise or do these events actually take place years ago? If this is set in the past than you have to use the laws that were in effect at the time, so that could change everything.
Delinquency of a Minor
Its interesting that this hypo uses the delinquency statute to charge the individual, since it is a very broad charge and Minnesota has a specific law for furnishing alcohol to a minor. (340A.503 Subdivision 2.) Whether this move was intentional or not, it would represent a mistake by the DA's office and, in my opinion, open some defensive doors. The actual furnishing statute does not allow any kind of defense for a good faith belief that the person was of legal drinking age, unless that belief were based on an authorized form of ID (driver's license, birth certificate, etc...) Read 340A.503 to see what I mean. But the delinquency statute doesn't limit this defense so I believe you could attack the mental state for the offense and argue that the Defendant did not know the girl was a minor and thus could not contribute to their delinquency. Another important point is that under the delinquency statute, a minor is defined as someone under the age of 18. So he'd only need to believe that she was at least 18, not 21. This also might explain why your hypo uses a "drinking age" of 18 and not 21. I don't think it is saying that the drinking age is 18, it probably just defines minor as someone under 18 because that's how its defined by the delinquency statute. The two statutes define minor differently.
For example, to understand the unwise move of using this statute as opposed to the furnishing statute, consider the same facts but as if the girl were 19 years old. The def. could not commit contributing to delinquency of a minor, because she is not a minor under that statute, she'd have to be under 18. But he could still be charged with furnishing to a minor, because under that statute a minor is defined as someone under 21.
This is all crap to throw out there, none of it is much of a defense. The defendant is guilty of either one of these charges (furnishing or contributing to del. of minor) because you said he actually served her at least one drink. Considering the way the night turned out, any judge or jury would convict on those facts. So you give and take. You tell them to go ahead and hold him responsible for that, and only that, because the other part of it (manslaughter) was just a tragic accident...not a criminal act.
Manslaughter
I have dealt with almost this exact hypo several times in real life, though in another state. We'd get calls like this when I was in the DA's office, but the facts were always that the parents served alcohol to their child and his/her friends and then someone tried to drive home and killed themselves. You can only charge them with furnishing alcohol. This is NOT manslaughter if all they did was serve some alcohol. You've got to look at what caused the death and what the defendant did and ask if there is any real connection and whether the defendant's actions were so reckless that it created the risk. If someone had died of alcohol poisoning, that's be one thing, but this is exposure. That is a freak accident and not nearly as foreseeable just by serving alcohol. The girl could just as easily have gotten lost while sober. The girl could have just as easily been of drinking age and still died of exposure under the same circumstances. Would he be charged with manslaughter then? Of course not, but why? Does the fact that she is underage really contribute to her death? Only very slightly because you can expect minors to be less responsible with alcohol, but does that difference create an unreasonable risk that she will wander off and die from exposure??? I think the notion is silly even for a mock trial. The crux of this issue for me is that she left the party with others and then went to a restaurant for some time and then left by herself to go home. How is the defendant reckless in regards to leaving her subject to exposure? She left with people. She went to another location where THEY were in control of the premises. If it was so unreasonable and such a clear risk to allow her, in her intoxicated state, to leave his presence than the same is true for the operator(s) of the restaurant. The same is true for her friends who let her walk home. Because once again, its really not the alcohol that killed her its the weather. Compare the defendant's actions to her friends. The Defendant let her leave, despite her intoxication, with multiple other people to care for her and I presume they left in a car which provides protection from the elements. Her friends let her leave, despite her intoxication, by herself with no means of transportation. Who is more culpable for her death? I think its her friends. It doesn't matter who served the alcohol, it matters that she was allowed to take that final walk home. The defendant wasn't the one who let her do that.
Also, you said she was intoxicated on marijuana. He didn't giver her that. How do we know it wasn't the marijuana that caused her become confused and get lost? There's too many variables to pin this on the defendant.
Unless there are other facts that you aren't telling us I don't see this as even being a close call. He left the victim in the care of others and she was safe for quite some time after that. Her later exposure is too far removed from the party and the alcohol for him to have known of that specific risk (exposure) much less consciously disregard it.
