Once we decide that Network Neutrality is a good thing to (re)enshrine in law, then we need to ask how to do that effectively. One way would be to pass a law saying, “Thou shalt not discriminate.” That’s the current approach. But network operators will say that they must manage their network, and if, in the course of network management, they were to disadvantage some source, destination, application, service or content, they might be accused of violating the law.
http://www.circleid.com/posts/net_neutrality_law_not_enough/