Where a Board representation decision partially grounded in an interpretation of the terms of the CBA conflicts with a subsequent artbitrator's ruling on the question of representation, the latter is unenforceable as to the representation, as the parties in the second proceeding are bargaining for the arbitrator's opinion, not the Board's interpretation of the Act.
http://media.ca7.uscourts.gov/cgi-bin/rssExec.pl?Submit=Display&Path=Y2018/D06-15/C:17-3492:J:Flaum:aut:T:fnOp:N:2171484:S:0
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.