Ahhh...see, I didn't say he didn't do enough, I said he didn't do it as well.
I mean, is it fair, no, its not. But then again, is have a class rank decided by one test per class fair? Is you future school decided on a standardized test with no real law in it fair? Is a person in the admissions office deciding if you have the mental capacity to do law school fair?
Your friend got unlucky, and the others in the class got lucky. Its what it came down to. The ethical problem would come if the professor told the students to look at that exact copy (wink wink sort of thing), yes that would be a major problem. But if they managed to look at the exact test the teacher copied from, then well, thats pretty good luck, and good for them. They guessed right. Sometimes, thats just what life comes down to, guessing right.