Where plaintiffs brought suit that was barred by res judicata and the plain language of governing contracts, district court did not err in imposing sanctions.The 7th U.S. Circuit Court of Appeals affirmed a decision by Judge Virginia M. Kendall, Northern District of Illinois. In 1997, Tai Matlin and James Waring co-founded Gray Matter Holdings LLC. In 1999, they entered into a withdrawal agreement with Gray Matter. The agreement entitled Matlin and Waring to royalties on the sales of certain key products. In 2003, Gray …