BigDave - 11:44 pm on May 9, 2005 (gmt 0)

You next step is to speak to an attorney, or drop it.

My guess is that they did what few ISPs would do and actually spent some time investigating your complaint. And for some reason (probably totally unrelated to AdSense) they disagreed with your appraisal that the sites were in violation of your copyright.

If they followed proper procedure, and can show their reasoning, they are almost certainly in the clear on the safe harbor provision, even if they are shown to be incorrect in court.

And don't expect a lawyer to take the case on contingency. I have gotten the impression that it is almost unheard of on copyright cases that are going to court, ass opposed to just writing threatening letters.