This paper is the introductory chapter for the forthcoming NBER volume Controlling Crime: Strategies and Tradeoffs. The Great Recession has led to cuts in criminal justice expenditures, and the trend towards ever-higher incarceration rates that has been underway since the 1970s in the U.S....

Countries today face numerous environmental policy challenges, such as climate change, air and water pollution, natural-resource management, natural disasters and environment-related hazards. The costs of not responding to them can be considerable, in some cases representing a significant drag...

As of this writing, the wars in Iraq and Afghanistan are in their eighth and tenth years, having accrued nearly a trillion dollars in direct military costs. I review the history of cost forecasts for these ongoing engagements, highlighting the differences across them in scope and accuracy,...

This paper attempts to provide a more complete reckoning of the costs of the Iraq War, using standard economic and accounting/ budgetary frameworks. As of December 30, 2005, total spending for combat and support operations in Iraq is $251bn, and the CBO's estimates put the projected total direct...

Outdoor air pollution kills more than 3 million people across the world every year, and causes health problems from asthma to heart disease for many more. This is costing societies very large amounts in terms of the value of lives lost and ill health. Based on extensive new epidemiological...