Vikings coach Brad Childress takes the stand in the Williams wall lawsuit against the NFL.Childress denied that he leaked the positive results of a doping test involving defensive linemen Kevin Williams and Pat Williams.He testified about the ``culture of honesty'' the Vikings organization has sought to create, and described his disappointment in Kevin Williams after the doping report first surfaced in October 2008.Lawyers made their closing arguments late in the day; the judge could rule some time in May.