It is an honor to comment on the article by Jack Mintz and Joann Weiner.' Both of the authors have a deeply knowledgeable background in this area. The paper that Jack Mintz published (with Michael Smart) in 2004 on provincial taxation in Canada is one of the most careful and interesting papers in all of international taxation.2 And Joann Weiner has clearly been studying formulary apportionment for a very long time, from both U.S. and European perspectives.
Avi-Yonah, Reuven S. "Commentary: More Open Issues Regarding the Consolidated Corporate Tax Base in the European Union." K. A. Clausing, co-author. Tax L. Rev. 62, no. 1 (2008): 119-24.