Employer bargained to lawful impasse, since the award of back pay at the time of impasse met the regulatory requirements. Parties had sufficient notice of the issues for jurisdiction.
Dissent: Employer improperly conflated the back-pay issue with other issues, and since the timing of the impasse determines the back-pay, simple declaration of impasse at a time when the disbursement was likely to be lawful doesn't establish that the impasse was per se lawful, since the bargaining that produced it seemed to put the back-pay in peril. No jurisdiction over this claim, as the employer didn't raise it.
https://www.cadc.uscourts.gov/internet/opinions.nsf/76C77F8449B89631852582C200522637/$file/16-1328-1739390.pdf
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.