(a)     The Authority shall determine the appropriateness of any unit. The Authority shall determine in each case whether, in order to ensure employees the fullest freedom in exercising the rights guaranteed under this chapter, the appropriate unit should be established on an agency, plant, installation, functional, or other basis and shall determine any unit to be an appropriate unit only if the determination will ensure a clear and identifiable community of interest among the employees in the unit and will promote effective dealings with, and efficiency of the operations of the agency involved.

      (b)     A unit shall not be determined to be appropriate under this section solely on the basis of the extent to which employees in the proposed unit have organized, nor shall a unit be determined to be appropriate if it includes--

      (1)     except as provided under section 7135(a)(2) of this title, any management official or supervisor;

      (2)     a confidential employee;

      (3)     an employee engaged in personnel work in other than a purely clerical capacity;

      (4)     an employee engaged in administering the provisions of this chapter;

      (5)     both professional employees and other employees, unless a majority of the professional employees vote for inclusion in the unit;

      (6)     any employee engaged in intelligence, counterintelligence, investigative, or security work which directly affects national security; or

      (7)     any employee primarily engaged in investigation or audit functions relating to the work of individuals employed by an agency whose duties directly affect the internal security of the agency, but only if the functions are undertaken to ensure that the duties are discharged honestly and with integrity.

      (c)     Any employee who is engaged in administering any provision of law relating to labor-management relations may not be represented by a labor organization--

      (1)     which represents other individuals to whom such provision applies; or

      (2)     which is affiliated directly or indirectly with an organization which represents other individuals to whom such provision applies.

      (d)     Two or more units which are in an agency and for which a labor organization is the exclusive representative may, upon petition by the agency or labor organization, be consolidated with or without an election into a single larger unit if the Authority considers the larger unit to be appropriate. The Authority shall certify the labor organization as the exclusive representative of the new larger unit.