The area where law and economics overlap is intensely interesting to me. The common law represents centuries of wisdom, for example, about who is responsible for what, under which circumstances. The section of law about righting wrongs between unrelated parties is called Tort Law. A central principal in torts is the concept of negligence. We expect people to know certain things, to expect certain things, and to take some care not to hurt anyone.
But accidents happen. Despite the protective glass, hockey fans get hit by pucks. And sometimes oil platforms explode.
So we have to decide who was harmed by whom, and how much the injury is worth. Putting values on things is what economics tries to do.