The EU is trying to dictate the law to companies that are doing business in Europe, not against the US government or congress. Which every country does on its territory. Note that the case is against Facebook, not the US government.
Some of these companies happen to be US companies. Who may be in a bind soon, as the European Court of Justice is likely to invalidate the Safe Harbor Agreement, as it usually follows the advice of its general attorney. If that happens, said US companies are no longer allowed to store data of EU citizens outside the EU, but at the same time they may be told by the US via national security letter to hand over those data.
If both the US and the EU stay adamant, companies like Facebook may have to choose between doing business in the US or in Europe.