In his letter, Wyden accuses the president of overstepping his authority by entering into an agreement which covers international trade and intellectual property. He explains that authority for both are explicitly assigned to Congress by the US Constitution.
His criticism also extends to the office of the US Trade Representative (USTR), who negotiated ACTA on behalf of the US, for misleading statements about its legality.
He wrote:
The USTR long asserts authority to enter ACTA as a "sole executive agreement" with no congressional authorization or approval. In its latest explanation on this topic, the ISTR stated:
ACTA is consistent with U.S. law and does not require the enactment of implementing legislation. The United States may therefore enter into and carry out the requirements of the Agreement under existing legal authority, just as it has done with other trade agreements.
This statement by the USTR confuses the issue by conflating two separate stages of the process required for binding the U.S. to international agreements: entry and implementation. It may be possible for the U.S. to implement ACTA or any other trade agreement, once validly entered, without legislation if the agreement requires no change in U.S. law. But, regardless of whether the agreement requires changes in U.S. law, a point that is contested with respect to ACTA, the executive branch lacks constitutional authority to enter a binding international agreement covering issues delegated by the Constitution to Congress' authority, absent congressional approval.
Besides the statement cited by Wyden, the USTR has also refused to disclose details of ACTA negotiations to the public, citing national security concerns. Exactly what national security issues are at stake have been explained.
If the president declines to submit ACTA for Senate ratification, Wyden is requesting he make an official statement clarifying that no portion of the agreement is legally binding on the United States.
He points out that the traditions of international law do not necessarily recognize the internal ratification processes of individual countries:
According to many international law scholars, customary international law recognizes the ability of the chief executive of a country to bind its nation to an international agreement regardless of domestic legal requirements.
I request that as a condition of the U.S. putting forward any official instrument that accepts the terms of ACTA that you formally declare that ACTA does not create any international obligations for the U.S. - that ACTA is not binding. If you are unwilling or unable to make such a clarification, it is imperative that your administration provide the Congress, and the public, with a legal rationale for why ACTA should not be considered by the Congress, and work with us to ensure that we reach a common understanding of the proper way for the U.S. to proceed with ACTA.
Of course, President Obama is unlikely to take either option. ACTA has been handled as a treaty by every country involved besides the U.S. and is obviously intended to mandate changes to the law.
If the United States were to back out, either through failing to ratify ACTA as a treaty or an executive statement nullifying its authority, the entire agreement would likely fall apart. The real question is what sort of formal legal challenge will be mounted, and by whom.