R.I. Gen. Laws § 28-7-15: Determination of bargaining unit.

The board shall decide in each case whether, in order to ensure to employees the full benefit of their right to self organization, to collective bargaining, and otherwise to effectuate the policies of this chapter, the unit appropriate for the purposes of collective bargaining shall be the employer unit, craft unit, plant unit, or any other unit provided, that in any case where the majority of employees of a particular craft make that decision, the board shall designate the craft as a unit appropriate for the purpose of collective bargaining.