The business groups claim that the regulations are making business harder for big companies to carry out transactions, referencing the proposed merger between U.S. drugmaker Pfizer and Ireland pharmaceutical company Allergan (both members of the Chamber of Commerce). That merger, projected to save the U.S. company about $35 billion in taxes, fell apart immediately after the new regs were released. See Michael Merced and Leslie Picker, Pfizer and Allergan Are Said to End Merger as Tax Rules Tighten, NY Times (Apr. 5, 2016). the lawsuit claims that Treasury did not have authority to issue the regulations and that there was insufficient notice to taxpayers under the Administrative Procedure Act.