Average percentage by which a bar-smoking ban in a US county increases the rate of drunk-driving fatalities: 13 Harper's Magazine, July 2008The source cited is Scott Adams, University of Wisconsin-Milwaukee, and this link (pdf) takes us to Adams' paper showing that the increase in road deaths arises from the extra distances that smokers travel to reach a bar where smoking is allowed. This illustrates a larger truth: that incremental evolution and adaptation along lines determined by current institutional structures often takes us away from the goals we actually want to achieve. In this instance pressure, presumably from anti-smoking lobbyists and well-meaning healthcare agencies, generates a rise in road deaths. Nobody actually has a strong incentive to look at the big picture.
A Social Policy Bond regime would be different. Broad outcomes, such as the general health of an entire population, could be targeted, giving people incentives to help improve it - rather than, as at present, to work on things (such as smoking restrictions) that sound helpful but that actually do nothing for the wellbeing of the population.