It is an unfair practice for an employee organization or its agents to:
(1) Restrain or coerce an employee in the exercise of the rights guaranteed by this chapter. However, this subdivision does not impair the right of an employee organization to prescribe its own requirements with respect to the acquisition or retention of membership therein;
(2) Restrain or coerce an employer in the selection of his representative for the purpose of collective bargaining or the adjustment of grievances;
(3) Cause or attempt to cause an employer to discriminate against an employee in violation of subdivision 3-18-3.1(3) or to discriminate against an employee with respect to whom membership in such organization has been denied or terminated on some ground; and
(4) Refuse to negotiate collectively in good faith with an employer, provided it is the formal representative.