A friend is considering raising some bees on a small scale in his backyard, he knows of someone else that has done this and found it interesting.

What are the rules and laws for doing this in your backyard, are there any?

To give you an idea of his space, he is in a townhouse with neighbors on only one side him (unfortunately that one neighbor is severly allergic to stings). His property line goes about 30 feet past the back of his home. What are the risks? Thanks for any help.