TPLC, Inc. and its equity interest holder, Telectronics Pacing Systems, Inc. (Telectronics) (defendants), manufactured and marketed the J-Lead pacemaker, a battery-powered device that regulates the rhythms of the heart. Eugene and Elise Owens and others (Owens) (plaintiffs) filed a class-action products-liability suit against Telectronics in federal district court. Owens alleged that the J-Lead devices were negligently manufactured or designed and thus defective. Owens claimed the retention wire used in the devices occasionally fractured, causing serious medical complications and sometimes death. The Panel on Multidistrict Litigation selected the United States District Court for the Southern District of Ohio to resolve over 400 cases. The district court initially certified a nationwide class, but decertified the class upon Telectronics’s motion for reconsideration. Owens filed a renewed motion for nationwide class certification on claims of medical monitoring, negligence, strict liability, and punitive damages.