An economist told jurors in Minnesota's tobacco trial that tobacco companies conspired to prevent the development of a less-harmful cigarette because doing so would throw the industry into a dogfight of competition. The testimony boosts State and Blue Cross Blue Shield claims that tobacco companies broke anti-trust laws by supressing research into smoking and health. Minnesota Public Radio's Elizabeth Stawicki reports: Economist Adam Jaffe told jurors the internal company documents show the tobacco companies have violated anti-trust laws by conspiring to restrict competition since 1953. Jaffe is a professor at Brandeis and has also served on the president's council of economic advisors. He told jurors tobacco companies underst