I applaud Carolyn's efforts in this area. She is absolutely right. Spammers are controlled by the market. If enough people are annoyed, they respond. If that action causes problems for an ISP it puts it in their economic interest to drop customers who cause such harm, ie the spammers.
Economic interest is often a far stronger and much more effective incentive than legal requirement.
And remember that I say this as the Technical Director of the largest ISP in Northern Ireland. We already have a fairly decent self-policing mechanism in place. So it looks like Internet professionals prefer to control spam by having net vigilantes like us track down spammers and report them to their ISPs. In fact, it would be fair to say that without us net vigilantes, the Internet would probably grind to a halt from the load these spammers would place on it. OK, I'm signing off for this column.