This lecture presents three cases: Bates v. Dow, a lawsuit brought by peanut growers against the producers of a pesticide that degraded their soil; the Alar case, in which environmental organizations and the media successfully pressured EPA to ban a carcinogenic pesticide used on apples; and the Texas Cattlemen's Association's lawsuit against Oprah Winfrey for her coverage of Mad Cow Disease. Using these three cases, Professor Wargo discusses the legal concepts of preemption and defamation. He gives an overview of their origin and use in regulating agriculture and protecting human health and the environment. Through the Texas Cattlemen's Association case, he shows the effect of state "veggie libel" laws on free speech.