Harvard Law School professors Lawrence Lessig and Jack Goldsmith took to the op-ed page of the Washington Post today to slam the Obama administration's approach to the Anti-Counterfeiting Trade Agreement (ACTA)—and to threaten a lawsuit if ACTA is signed without Congressional oversight.

The US has positioned ACTA as an executive agreement rather than a treaty. Such a move means that ACTA doesn't need Senate approval, but it also means that the agreement should not alter US law, either. If you want to change the law, you go to Congress.

Lessig and Goldmsith argue that ACTA, at least it its current leaked form, does involve "ideas and principles not reflected in US law."

Example number one is a pretty poor choice, in our view; the professors say that "ACTA could, for example, pressure Internet service providers—such as Comcast and Verizon—to kick users offline when they (or their children) have been accused of repeated copyright infringement because of content uploaded to sites such as YouTube."

As we've noted before, though, the language here comes from the Digital Millennium Copyright Act—already US law. The leaked drafts show that ISPs need policies in place to deter repeat infringement; a footnote suggests that "three strikes" Internet disconnections might be one appropriate way to do this, but would not be required.

The more fundamental complaint is that the president simply doesn't have the power to negotiate executive agreements on IP law and communications policy.

"The administration has suggested that a sole executive agreement in this instance would not trample Congress's prerogatives because the pact would not affect US domestic law," write the professors. "Binding the United States to international obligations of this sort without congressional approval would raise serious constitutional questions even if domestic law were not affected."

They recommend that Congress stand up for its rights and insist on being consulted—something that (now Vice President) Joe Biden did to the Bush administration when he was a senator. If ACTA is signed without such oversight, Lessig and Goldsmith say it will "be challenged in court."