Cato claims the numbers expounded by SOPA's backers, and repeated by their whores in congress, are bullshit.
Basically, MPAA claims online piracy costs the U.S. economy $200-250 billion per year, and had killed 750,000 American jobs.
This article, in tracking down those claims, and checking with the GAO, show piracy...
1- Costs the US economy nothing, zip, zero.
2- Costs the Hollywood studios $445 million, which equals the gross for the last Alvin & The Chipmunks.
3- Costs zero US jobs, except maybe employment in copyright-intensive sectors (lawyers).
Also, implementation would cost the taxpayers $47 million a year, plus untold millions more in ISP compliance costs which would be passed on to the consumer.