In a speech today at the Tax Policy Center, Treasury Secretary Jack Lew said the agency will decide “in the very very near future” how it will respond to the recent wave of tax-motivated corporate inversions.  Lew strongly urged Congress to curb the practice on its own, but suggested Treasury might move administratively if lawmakers did not act. He gave few hints about what that response would be, however. Lew said a legislative fix should be retroactive to last May and urged Congress to act quickly, as the White House has said throughout the summer. But, he added, “The administration is clear-eyed about the possibility that Congress may not move as quickly as necessary to respond to the growing wave of inversions.  Given that, the Treasury Department is completing an evaluation of what we can do to make these deals less economically appealing.” After his presentation, a panel of tax and regulatory experts debated whether Treasury has the authority to act administratively against inversions and, if so, whether it should take such a step. Not surprisingly, the panelists disagreed. Three-- Harvard law professor Steve Shay, TPC’s Steve Rosenthal , and NYU law professor Sally Katzen-- suggested Treasury does have broad power to act. “There is no doubt,” said Shay. “Of course, Treasury has the authority,” said Rosenthal. John M. Samuels, Senior Counsel of Tax Policy & Planning at General Electric Co., disagreed. “I don’t think they have legislative authority,” Samuels said. He called such rules “a dangerous precedent” that could damage the integrity of the Treasury’s tax professionals—a point that Katzen strongly rejected. Yet Samuels seemed to support claims that these deals are structured primarily to avoid tax. Asked whether firms moving their legal address overseas costs U.S. jobs, Samuels replied, “No jobs leave the U.S…, no capital leaves the U.S….management can still stay.” The panelists agreed with Lew that even if Treasury has authority to curb inversions, it would be far better—and more effective—for Congress to limit the practice, even if that statute fell short of broad-based corporate reform. Even Steve Shay, who has been an outspoken advocate of Treasury action, acknowledged that regulations could only limit—but not stop—inversions. “Some deals would still go forward,” he said, “to the extent they are good business deals.” Katzen noted that agencies can interpret that law, but not rewrite it. And she added that it is much more difficult for Treasury to impose retroactive limits on an activity than it is for Congress to adopt curbs on past transactions. The panelists also disagreed on the urgency of the problem. Shay said the recent wave of inversions has already pulled a substantial amount of money out of the corporate tax base: “We’re talking about real money.” But, he added, the real issue is about “protecting the integrity of the tax code.” Samuels disagreed, insisting “the house is not on fire” and argued that, based on congressional Joint Tax Committee estimates of the revenue that could be generated by anti-inversion legislation, relatively few dollars are at stake. The panelists also disagreed over what anti-inversion regs would mean for corporate tax reform. Samuels predicted Congress could approve such a measure within two years but argued that Treasury would slow the effort by aggressively imposing regulatory curbs on inversions. “Comity,” he said, “would be destroyed.” But Katzen suggested it was already hard to find comity on Capitol Hill. Samuels’ argument, she said, “is not very persuasive.”