From New Process Steel, L.P. v. NLRB:
The Taft-Hartley Act, enacted in 1947, increased the size of the National Labor Relations Board from three members to five. Concurrent with that change, the Taft-Hartley Act amended §3(b) of the National Labor Relations Act to increase the quorum requirement for the Board from two members to three, and to allow the Board to delegate its authority to groups of at least three members. The question in this case is whether, following a delegation of the Board’s powers to a three-member group, two members may continue to exercise that delegated authority once the group’s (and the Board’s) membership falls to two. We hold that two remaining Board members cannot exercise such authority….
Section 3(b), as it currently exists, does not authorize the Board to create a tail that would not only wag the dog, but would continue to wag after the dog died.