Steady declines in smoking, a big win for public health, are creating problems for municipal bond investors. A handful of bonds backed by yearly payments from tobacco companies under a landmark settlement with 46 states are in the earliest stages of default, and more distress is expected. Dozens of states, counties and cities issued the bonds to receive billions of dollars upfront from the 1998 settlement. But now they are seeing smaller payments than expected from the companies as tobacco sales decline in America. There is also a renewed legal battle between the states and the tobacco companies, with the...