After being fired from Saginaw Chippewa Casino in 2010 over union organizing, Susan Lewis took her case to the National Labor Relations Board. The board ruled in favor of Lewis ordering her reinstatement. The Saginaw Chippewa Casino claimed that the NLRB had no jurisdiction over the casino as tribal law protects it. If it is proved that the NLRB cannot control labor practices in tribal businesses, workers will no longer be able to unionize.
See "High Stakes for Tribal Casinos in Court Fight Over Labor Rights", Amanda Becker, Business Insider, September 15, 2014