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I have no way of knowing whether B- is a reasonable grade or not for this paper. If it is, then I probably haven't learned much about law and justice from it. If it isn't, I don't know what I've learned. Is the argument not expressed in a lawyerly way? Are the conclusions grossly incorrect? Are the referenced decisions misinterpreted?
If the professor gave written comments, it would be interesting to see them (with her permission, I guess, although that's not ethically or legally clear).
It would also be interesting to see what an "A" answer was.
PS As an MIT undergraduate, I also crossregistered at Harvard for things not offered at MIT. For instance, biology at a level above that of the cell. I did learn some physiology in that course, but I also learned something about pre-meds, since it turns out that very few people take this course because they're budding scientists.
My first mountain bike (bought as a city bike) was a revelation. It had a stiff frame, effective brakes, a wide range of gears, and I could see the road ahead.
It was fine for my short commute for a few years. But longer rides were uncomfortable. I blamed myself for being out of shape. Still, I appreciated its gear range when (e.g.) bicycling uphill from Bomarzo (see PhilG's beautiful photos) to Viterbo.
After a fair amount of research (including Forrester's Effective Cycling), I decided to buy a touring bike. It, too, had a stiff frame, effective brakes, and a wide gear range. It took me a while to figure out how to keep my back straight instead of craning my neck, but once I did that, it became far far more comfortable than the mountain bike, even for short rides. Unfortunately for buyers' choice, touring bikes (the ones with the gear levers at the end of the handlebars) are unpopular; the silver lining is that they are also unpopular among bike thiev...
This is not central to your argument, but it turns out that a substantial proportion of law school graduates do not in fact practice law. They do, however, use their legal training to make money. But I can't point to figures.