A few decades ago, marijuana was a topic that relatively few people, mostly counterculture musicians and comedians, spoke about in public. The comedy team of Cheech and Chong made films such as "Up in Smoke" that extolled the pleasures of smoking pot at a time the subject was still taboo."When trouble times begin to bother me," they sang, "I take a toke and all my cares go up in smoke." On the fringes of American society, it was usually possible to find activists who wanted to legalize it, as the reggae artist Peter Tosh famously sang. Efforts to legalize the...