(FORTUNE Magazine) – Known as a ''lawyer of last resort,'' Harvard professor Alan Dershowitz has tried to put up the best defense for a Dickensian lineup of suspects: accused murderers, pornographers, terrorists, racists, granny-exploiting nursing home operators -- not to mention Claus von Bulow. But in his latest case, he thinks he's on the side of the angels. A plaintiff named Joanne Kotler is suing three tobacco companies over the death of her cigarette-addicted husband. Dershowitz, 51, is advising Kotler's counsel at Boston's Nissen & Lumsden. The impassioned civil libertarian sees constitutional issues in his new battle, arguing that judges have unfairly kept tobacco cases from reaching juries, thus abrogating the Seventh Amendment right to a jury trial. He would like a jury to decide three critical issues: Does smoking lead to cancer, emphysema, and heart disease? Did some companies, aware of the dangers way back in the 1940s, deliberately engage in fraudulent campaigns to persuade people that cigarettes were healthy? And what do tobacco merchants owe families of deceased smokers? Dershowitz, who has turned down lucrative offers to defend tobacco companies, is working pro bono. ''The plaintiffs' lawyers are outmanned,'' he says. ''I hate unfair fights. So much talent has been sold to the other side. They've tried to buy almost every lawyer I know.'' Making him the last resort.