Sumner Redstone's attorney Robert Klieger argues that a lawsuit challenging his client's mental competency should be dismissed. Click here to see video from the hearing. 

Canton - Attorneys for Sumner Redstone and daughter Shari Redstone asked a Massachusetts probate judge on Thursday to throw out a lawsuit claiming the ailing 93-year-old media mogul is mentally incompetent, in a case that could determine control of major companies like Viacom, CBS Corp. and Paramount.