Who is in charge of international agreements seems to be the point of contention here.http://www.wired.com/threatlevel/2012/03/acta-congressional-approval/
Sen. Ron Wyden (D-Oregon) says the Obama administration must secure congressional approval for the United States to participate in an international anti-piracy treaty, a position at odds with the president.
The accord, known as the Anti-Counterfeiting Trade Agreement, exports on participating nations an intellectual-property enforcement regime resembling the one in the United States. Neither the United States nor any other country has ratified the deal, which was brokered by both the President George W. Bush and the President Barack Obama administrations and finalized in October.
“I believe Congress should approve binding international agreements before the U.S. is obligated to comply with those agreements
The President claims that ACTA is already legitimate as it makes no changes to existing US laws but many do not agree and if changes are created ACTA cannot be legal as it has to pass through congressional assent so this is an important legal challenge to its possible legitimacy in the US, it stands to reason if its not deemed legitimate in the country most hard at work exporting its draconian financial penalty demands its likely to fall out of favour abroad.