There have already been attempts to restrict their use, written into proposed U.S. legislation, as just one example. And I can't disagree with your comment, "w

There have already been attempts to restrict their use, written into proposed U.S. legislation, as just one example. And I can't disagree with your comment, "won't require any new laws to be passed", either. Again in the U.S., Federal authorities have already and are increasingly demonstrating willingness to act in extra-judicial fashion. It's not too much of a leap from ISP reporting to demands that ISP's detect and shut down such pipes (think of the "terrists", the children, the poor starving record labels and producers, etc., etc.). What the ISP's really want, is release from any and all liability. That is one aspect of the recent CISPA negotiations. As long as they can't be sued nor otherwise hauled into court, they may view "shutting down the pipes" as one more avenue for shoving users onto their own, in-house services.