[icebraining]

By themselves, laws don't prevent actions (see copyright infringement), you need enforcement, and if a very large fraction of the population starts using Bitcoins, it can be very hard to stop, at least without taking some very drastic measures.

My guess is that the US government would just get enough computing power to control the network and prevent it from working well.

[zanny]

The latter seems very likely if btc every became really popular. It would probably send the United States into a radical depression and destroy its economy, but by then the ~500 Americans that own the world would have flown the coop anyway, and all that USD they had would still be worth something.