What is the legal test for an employer's refusal to bargain with a union after a contract expires?

Once an employer has recognized a union, the union is conclusively presumed to command majority allegiance. NLRB v. Wilder Constr. Co., 804 F.2d 1122, 1124 (9th Cir.1986). This presumption becomes rebuttable after a contract expires. Id. The company's subsequent withdrawal of recognition and refusal to bargain establishes a prima facie case of unfair labor practice. Id. "There is a continuing duty on the employer to recognize and to bargain with the union until the presumption of majority support is rebutted." Id. Refusal to bargain may be justified if the employer had a "good faith doubt" as to the union's majority status. Id.