In New York a group of middle-aged professional people begin an evening with a marijuana "cocktail party." in Detroit some lawyers and executives get together in the small hours for wine-and-pot. In Beverly Hills, at a stately black-tie dinner, the matronly hostess beckons the butler who brings a silver tray with a single after-dinner joint to be passed around.Marijuana, until recently a conspicuous liturgy of the rebellious young, is spreading into the middle class and fast becoming an institution. An estimated 12 million Americans have now tried it. The consequence is an ironic contradiction reminiscent of the Prohibition era of the 1920s, when ordinary citizens blithely drank bathtub gin while cops pursued the bootleggers. Now as the pot party gets to be fashionable in some circles, authorities are mounting an unprecedented campaign to cut off the supply at the Mexican border, where U.S. Customs agents are bearing down on professional smuggling, with planes, boats and mobile radar units.A growing body of opinion now recognizes the disproportionate severity of laws that define mere possession of marijuana as a felony and lead to travesties like the case of a 20-year-old college student sentenced to 20 years for possession (p. 30). Last week the Nixon administration reversed its adamant earlier position and recommended reducing the federal penalty for first offenders to a misdemeanor.As illegal marijuana becomes increasingly "respectable," ultimately the whole question of legalization will have to be faced-although no country in the world officially sanctions it. On page 34 Dr. James Goddard, former director of the Food and Drug Administration, dispels many of the myths that confuse the marijuana debate and renders his verdict on legalization.