On November 30, 2011, the US Circuit Court of Appeals for the Seventh Circuit issued an opinion in Committee of Concerned Midwest Flight Attendants v. International Brotherhood of Teamsters Airline Division and Teamsters Local 135, reversing the district court's grant of summary judgment for the defendant unions. The court determined whether the seniority lists of two merged airlines must be integrated when the acquiring carrier:

Under the McCaskill-Bond Amendment to the Federal Aviation Act (FAA), when, in a covered transaction, air carriers merge into a single carrier, the seniority lists of the merged entities must be integrated. That is, union members of the acquired airline must be integrated into the seniority lists for the surviving entity and its unions rather than placed at the bottom of them. A transaction is covered by the McCaskill-Bond Amendment if it:

Republic Airways Holding, Inc. (Republic Airways), the parent of Republic Airlines, acquired Midwest Air Group, the parent of Midwest Airlines in July 2009. Republic Airways integrated the operations including routes and scheduling of Midwest Airlines with its other subsidiaries, and brought each of the subsidiaries under common management and labor relations departments. By November 2009, Republic Airways:

Republic Airways planned to merge the seniority lists for Midwest Airlines flight attendants, depending on the results of a representation dispute involving the Teamsters who represented Republic Airways's flight attendants and sought to represent the flight attendants of Midwest Airlines and other recently acquired subsidiary airlines (see In re Chautauqua Airlines/ Shuttle America/ Republic Airlines/ Midwest Airlines/ Frontier Airlines/ Lynx Aviation). In that case, the National Mediation Board (NMB) concluded that the Teamsters would represent the flight attendants from the then dissolved Midwest Airlines in a single bargaining unit including flight attendants from Republic Airways's other subsidiaries. The NMB found that the single bargaining unit was appropriate because Midwest Airlines's former operations had been sufficiently integrated into Republic Airways's operations and constituted a single transportation system.

After the NMB's decision, the Teamsters took the position that if the furloughed Midwest Airlines flight attendants were rehired, they would be placed at the bottom of the seniority roster. Three of the furloughed Midwest Airlines flight attendants and a committee claiming to speak for all of them, sued the Teamsters alleging a violation of the FAA and demanding that their seniority at Midwest Airlines be integrated into the Republic Airways-Teamsters seniority system, so that they would not be placed at the bottom of the seniority roster. The seniority roster customarily determines, among other things, priority for recall of furloughed union members to vacant positions but may affect other employee rights under a collective bargaining agreement (CBA).

The District Court for the Eastern District of Wisconsin granted the Teamsters' motion for summary judgment on a motion for reconsideration. The court held that Republic Airways's purchase of Midwest Air Group was not a transaction covered by the McCaskill-Bond Amendment. It found that Republic Airways purchased assets but not an air carrier because it abandoned Midwest Airlines's certificate to engage in air transportation.

The plaintiffs appealed to the Seventh Circuit.

The Seventh Circuit analyzed Republic Airways's purchase of Midwest Air Group under the McCaskill-Bond Amendment and reversed the district court's decision. In particular it held that the transaction:

In light of this decision, airlines must understand that acquiring or merging with other airlines may impute seniority list requirements impacting the seniority for existing and new union-represented employees. In light of this decision, airlines that are considering acquiring or merging with another airline should: