In recent history, the UK has liberalized its rules concerning the hours that pubs can operate. For example, the Licensing Act of 1988 expanded Sunday hours and no longer required pubs to close for two and a half hours in the afternoon. In 2005, the law in England and Wales was further liberalized such that pubs could remain open until 5 am instead of closing at 11 pm. An article in the latest issue of the Journal of Health Economics claims that the 2005 liberalization of pub hours actually decreased the number of traffic accidents.
Theoretically, extended pub hours could either increase or decrease traffic accidents. Obviously, if people drink at a steady rate, they will usually become more intoxicated as the night progresses; extending pub hours could lead to more dangerous drivers. However, there are other ways that extended pub hours might plausibly reduce accidents. Without early pub closings, fewer pub patrons would make an additional drive to a second drinking location -- such as to a party at a friend's house. A later pub closing might also cause drinkers to drive home during hours with fewer cars are on the road.
Proponents of liberalized pub hours saw other benefits:
The initial government White Paper, Time for Reform ..., contended that the uniform and early closing hour meant "that large numbers of drinkers come out onto the streets late at night at the same time causing disorder." It also contended that early closing caused a "beat the clock" game that encouraged binge drinking. Famously, MP Jane Griffiths is quoted claiming that "The effect of compulsory closure has been for people to drink 'against the clock', with whole generations of young people learning to drink as much as possible in a short space of time ..., Most of these young people are drunker than they would be if they drank at their own pace..."
During the time period under study, Great Britain saw generally declining traffic accidents and fatalities. For example, from 2000 to 2005, traffic fatalities and serious injuries fell from 41,000 to 32,000. The paper isolates the impact of the law from long run traffic trends by comparing England and Wales to Scotland -- the 2005 changes did not impact Scotland. The reduction in traffic accidents for England and Wales are plausibly related to the change in pub hours because the largest reductions occurred during weekend nights and early mornings. The impact on young drinkers was particularly strong. Accidents involving young people on Friday and Saturday nights decreased by an estimated 32.5 percent.