A federal judge has refused to dismiss a trio of antitrust lawsuits against pharmaceuticals giant GlaxoSmithKline that accuse the company of using a series of illegal tactics to delay the approval of generic versions of Flonase, a popular allergy drug.

Lawyers for GSK argued that all of its conduct is immune from antitrust liability under the Noerr-Pennington doctrine, but U.S. District Judge Anita B. Brody found that the plaintiffs may be able to prove that the conduct was nothing but a "sham" that enjoys no such immunity.