I assume you mean packet filtering. If so then I say by all means they should bring it on. If an ISP does this and they don't filter data propperly and something gets by then the RIAA still has no case simply by the fact that the ISP can say "hey we filter all content and if it got by then it was what you claim it is". As long as it would still be possable to share uncopyritghted material. Besides if the ISP filters everyone then it'll also filter the RIAA in their illegal measures to gain unlawfull info from the ISP's users which also protects an ISP's user in another way.