If the feds can shut down Megaupload why do we need SOPA

Supporters of the Stop Online Piracy Act say it's needed to combat "rogue sites." Yet Megaupload got shut down under existing laws.

Does the Megaupload raid prove SOPA is unnecessary, or not?

Source:
http://arstechnica.com/tech-policy/news/2012/01/if-the-feds-can-shut-down-megaupload-why-do-they-need-sopa.ars