N.Y. WKC Law § 91

§ 91. Groups for accident prevention. For any group established under\nthe provisions of section ninety membership in the group of any employer\notherwise entitled to be admitted thereto may be conditional upon\nacceptance and maintenance of special rules as to administration and as\nto accident prevention and medical care of employees. Such limitation of\nmembership in the group may be established only upon proper evidence\nthat a majority of the members of the group have approved such rules and\nonly when such rules have been approved by the commissioners as\nsufficient to constitute a proper basis of differentiation as to\nmembership in the group.\n