The House bill (H. R. 3261) referred to as the Stop Online Piracy Act (SOPA) bill, or completely known as the bill "To promote prosperity, creativity, entrepreneurship, and innovation by combating the theft of U.S. property, and for other purposes" has pitted the Southern Californian Hollywood immorals against the Northern California Silicon Valley immorals.
The motivation is stop web sites from posting including selling copyrighted material -- music, video, etc. -- without the approval of the artists or content providers. Whereas most of the offending sites are based outside of the USA, the proposed law would require U.S. search engines, advertising networks and other providers to block access to those sites and payments sites could not transfer funds to them. The law also would hold those US firms that facilitate this -- knowingly or not -- responsible and liable.
There are dolts running around who hate the legislature because it impacts their ability to access content for free. In their mind, there is no such thing as copyrighted material. These are those that have never bought a CD in their lives; why should they, music is free.
Others; e.g., the content providers, want to stop all leaks of content and do not want to give away what has value.
Illegal file-sharing via peer-to-peer or file lockers, cannot be justified as being fair to the content providers. For example, Megaupload based in Hong Kong generated around $175 million per year in selling copyrighted material -- material they do not own nor pay rights, royalties or remuneration for.
The problem is real but another massive law is not going to solve this issue. Search engine firms are pro-active and shutting down sites selling or sharing unauthorized materials. Fiddling with DNS by filtering out specific domains on a massive scale does not seem prudent. Content filtering companies offer this service today.
Like most legislation, SOPA (and PIPA) are motivated by specific groups. And the bottom-line is that it is financially motivated. This one sounds like certain Democrats providing paybacks to their Hollywood supporters. it has nothing to do with what is right or best for the nation.