What should you do if you know someone breaking the copyright law?

I have to write a report for school about a person (John) who buys a computer game and then copies it and sells the copies.

What should I do if I know that a friend is breaking the law? I'll explain to him that he is breaking the law and that he should stop. But should I report him? If so, where?

Its not up to you. he knows he is breaking the law. don't tattle.