DMCA Enforcement

Sorry to those North American operators who aren't in the US for this slightly off topic query. How do upstream providers here deal with DMCA violation reports? When several tiers seperate the backbone from the end customer, should everyone respond? Should the top tiers pass it down to their customers to deal with? The DMCA itself seems pretty vague here, how are you guys dealing with this, and how have your respective legal teams interpreted who needs to get involved? Thanks, Kevin (P.S. Any ISDN gurus here who don't mind answering a quick question, if you could contact me off list, it would be very appreciated)