How is the class graded? On a curve or not?

If the class is graded on a curve, then Louis' cheating IS unfair to the rest of the class. Proceed with Leed's advice in this case.

If the class is not graded on a curve, then Louis' cheating is NOT unfair to the rest of the class. He did obtain an unfair advantage for himself, but he did not harm others in the course of obtaining an unfair advantage for himself. So, I would relax.

In the case of:

"When my sister was in college, a pair of students broke school rules: they were in love and living together in a dorm. It was common knowledge, but blatantly flaunted the conservative school's code of conduct. An acquaintance reported their living arrangements to the dean. The young couple were punished, but the young man who reported them was also punished: his fellow students went out of their way to ignore him, snub him, and otherwise ostracize him. He graduated but was friendless. "

The living arrangement of the young couple in love only violated some formal and probably meaningless code of conduct. Their living arrangement did not harm anybody. It is one thing to report a bully who is making life miserable for a weaker, smaller victim and a completely different thing to use the formal code violation as a way to make life difficult for people who are completely harmless. And ... students KNOW that. Students would not ALL "go out of their way to ignore ... snub ... and otherwise ostracize" someone who reports a bully. SOME people would, out of fear of the bully. OTHERS would appreciate the courage that it took the reporter to report the bully. So some people would react this way and other people would react that way. That everybody reacted the way they did in the case of reporting the formal code violation on the part of a harmless couple was to be expected.