A huge pharmaceutical merger is off: Pfizer of New York has put a halt to a $160 billion deal with Allergan of Ireland. Pfizer was after Allergan’s Irish street address so it could lower its U.S. taxes in a maneuver known as an inversion. That changed after the U.S. government decided to clamp down on tax-inversion rules on Tuesday. 

Don’t be surprised, though, if someone tries to challenge these new rules. 

“Who knows if someone’s going to go running to court saying that the Treasury secretary has exceeded his authority,” said Marketplace regular and Washington Post columnist Allan Sloan. “There are 355 pages of this stuff. And that gives you hundreds and hundreds and hundreds of places where somebody can find loopholes.” 

Click the above audio player to hear the full interview with Sloan.