I’m sure the Maine Revenue Service is closely watching this battle between Massachusetts and New Hampshire.  Apparently, MA wants NH businesses to collect their sales tax for them when one of their residents goes cross-border shopping.  Clearly this would be a violation of the U.S. Commerce Clause and will hopefully be bounced right out of court.  From an economic standpoint MA should be careful, if Bay Staters cannot reduce their tax burden by cross-border shopping they may resort to cross-border migration.  In fact, MA has already lost almost 300,000 residents to other states since 2000.