The New York times as a good piece on prisons, police and crime:
“The United States today is the only country I know of that spends more on prisons than police,” said Lawrence W. Sherman, an American criminologist on the faculties of the University of Maryland and Cambridge University in Britain. “In England and Wales, the spending on police is twice as high as on corrections. In Australia it’s more than three times higher. In Japan it’s seven times higher. Only in the United States is it lower, and only in our recent history.”
…Dr. Ludwig and Philip J. Cook, a Duke University economist, calculate that nationwide, money diverted from prison to policing would buy at least four times as much reduction in crime. They suggest shrinking the prison population by a quarter and using the savings to hire another 100,000 police officers.