In the debate over tax inversions–that little corporate maneuver to reincorporate abroad to avoid U.S. taxes–there’s a little fight going on about a small but significant issue: if legislation passes to stop this scam, should it be retroactive? Of course it should.

This just came up during a Senate hearing. Republicans, in particular Orrin Hatch, are throwing up all sorts of objections (phony of course) to try to block a serious bill to end this robbery. As Citizens for Tax Justice explains, whether the bill should be retroactive is one of the objections:

As for Hatch’s opposition to any retroactive change in the tax law, waiting even a couple weeks could result in more corporations that merge and claim to be foreign and able to avoid U.S. taxes forever. And a retroactive provision is not particularly burdensome for these corporations, which are on notice that such a change is likely to apply to any deals made from May on and are able to plan accordingly. In fact, Medtronic and other aspiring inverters are actually writing provisions into their merger agreements that allow them to walk away from the deals if Congress changes the rules to deny the tax benefits of inversion.

As I’ve pointed out before, the whole maneuver is a scam. So, making it retroactive it entirely in the public interest. Not that Hatch cares.