This opens up the door to censorship too though, so it has to work like the web does now: individuals and groups can select whether to serve things or not depending on their own views. Same for Routing.
Even if, say, someone published a list of known illegally-transmitted copyrighted files, you could still make a strong argument that you don't trust the source of the list and would need to receive and review a specific report of each instance of copyright violation that went through your service, like the current DMCA model. (Again, though, not a lawyer.)
People shouldn't accidentally store illegal things they don't mean to (hence blacklists) but you also don't want to snuff out freedom of speech of those who understand + are willing to take the risk. The issue is routing access to it is also considered hosting it (dcma takedowns for links on the web).
I think that the best thing is to have the default DHT include blacklists that can be updated to handle DMCA requests. Sort of like DNS works today. Definitely something that we'll have to figure out as time goes on.