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

So if the US government already has the power to arrest people and seize assets in places as far away as Germany, New Zealand, and the Philippines, are the new enforcement powers sought by content companies even necessary?

We posed that question to two people on opposite sides of the SOPA debate. Cara Duckworth is a spokeswoman for the Recording Industry Association of America. And Julian Sanchez is a research fellow at the Cato Institute and an occasional contributor to Ars Technica.