(a) A voluntary recognition or collective-bargaining agreement between an employer primarily engaged in the building and construction industry and a labor organization will not bar any election petition filed pursuant to section 9(c) or 9(e) of the Act absent positive evidence that the union unequivocally demanded recognition as the section 9(a) exclusive bargaining representative of employees in an appropriate bargaining unit, and that the employer unequivocally accepted it as such, based on a contemporaneous showing of support from a majority of employees in an appropriate unit. Collective-bargaining agreement language, standing alone, will not be sufficient to provide the showing of majority support.

(b) This section shall be applicable to an employer's voluntary recognition extended on or after the effective date of this rule and to any collective-bargaining agreement entered into on or after the date of voluntary recognition extended on or after the effective date of this rule.