Keds, LLC (Lexington, MA) and its licensor have sued several competitors for trademark infringement relating to a blue rectangle placed at the heel of footwear. Because the mark has been registered since 1959, Keds even throws in a cite to a 1989 First Circuit case calling the mark strong and incontestable. So there.
Keds, LLC v. Four Star Distribution, 11-12217-RWZ (D. Mass. Dec. 14, 2011)
Keds, LLC v. One-Distribution Company, LLC, 11-12219-RWZ (D. Mass. Dec. 14, 2011)
Keds, LLC v. Vans, Inc., 11-12222-RWZ (D. Mass. Dec. 14, 2011)