Louisiana shouldn't be allowed to pursue its own antitrust suit over Flonase nasal spray years after it was a member of a class that settled a nearly identical case, GlaxoSmithKline told the Third Circuit on Wednesday, arguing that a Pennsylvania federal court's decision to the contrary could invite "destabilizing gamesmanship."

GSK is represented by Stephen J. Kastenberg, Burt M. Rublin, and Jessica M. Anthony of Ballard Spahr LLP, and Lisa S. Blatt, R. Stanton Jones, Sarah M. Harris, Robert Leider, and Sally L. Pei of Arnold & Porter LLP.

Louisiana was a member of the settlement class in a lawsuit brought by indirect purchasers who sued GSK for allegedly hindering the ability of a competitor to bring a generic form of the allergy drug to market. The class members, including Louisiana, relinquished any claims they may have against GSK in exchange for GSK paying $150 million, the company said in its opening brief to the Third Circuit.

Rather than that being the end of the matter, Louisiana sued GSK two years later in its state court making the same antitrust claims that were resolved by that settlement, filing a complaint that was nearly identical from the indirect purchasers’ complaint, GSK said.

GSK subsequently asked the Pennsylvania federal court that approved the 2013 settlement to enforce the stipulations in the deal by prohibiting Louisiana’s attorney general from pursuing any claims in the state lawsuit that were covered in the settlement release.