When co-respondent labor union petitioned the National Labor Relations Board to represent a unit of employees at respondents residential care facility, respondent objected to the inclusion of its registered nurses in the unit, arguing that they were "supervisors" under §2(11) of the National Labor Relations Act (Act), 15 U. S. C. §152(11), and hence excluded from the Acts protections. At the representation hearing, the Boards Regional Director placed the burden of proving supervisory status on respondent, found that respondent had not carried its burden, and included the nurses in the unit. Thereafter, respondent refused to bargain with the union, leading the Boards General Counsel to file an unfair labor practice complaint. The Board granted the General Counsel summary judgment on the basis of the representation determination, but the Sixth Circuit refused to enforce the Boards order. It rejected the Boards interpretation of "independent judgment" in §2(11)s test for supervisory status, an