It is hard to tell how effective spam laws are, as you don’t hear much about prosecutions for their violation. I suspect the reason is that such events are few and far between. Case in point: Australia just nailed the first spammer under their law – one that has been in place for a few years now.
It took the US a little over a year to nab their first spammer under CAN-SPAM. The bust resulted in a settlement that some would consider a bit weak.
A law without teeth is hardly a law at all. How tough do you have to get to stop the nonsense?