There is your congress at work

Bachmann bill would ban global currency.

They can ban global currency all they want, but nothing will prevent the other countries from NOT using dollar as the default reserve currency. Who is or will became the global economy leader is not determined by US law, it is determined by productivity. Who ever got the products most other country wants, their currency will be more sought after. It is a bit over simplify, but the long term trend will be determined by that.