Unless you're in a state that permits people to sue spammers for lost bandwidth and harassment, it seems to me that you'll have to make your case based on the economics of the situation. For example, try to demonstrate one or more of the following:

• that the revenue generated from spamming does not justify the expenditure of time and money finagling IP addresses to stay ahead of the ISPs and maintaining specialized servers.
• that you as a programmer would be better utilized if called upon to actually build something of value.
• that you are experiencing or expect strong customer backlash.

Good luck!!