In American Hospital Association v. NLRB (AHA), 499 U.S. 606 (1991), the Supreme Court addressed a challenge to a rule defining collective bargaining units for acute care hospitals. The plaintiffs there argued that because Section 9(b) of the NLRA requires the Board to make bargaining unit determinations in each case, the Board could not use its general rulemaking power under Section 6 to define bargaining units. The Court determined that because Section 9(a) authorizes the Board to decide whether a designated unit is appropriate for the purposes of collective bargaining, it could promulgate a rule proactively defining collective bargaining units in acute care hospitals, rather than determining the composition of such units through case-by-case adjudication. The Court noted that as a matter of statutory drafting, if Congress had intended to curtail in a particular area the broad rulemaking authority granted in 6, we would have expected it to do so in language expressly describing an exception from that section or at least referring specifically to the section. (AHA, 499 U.S. at 613.(