There's a much easier way of preventing crime: a) allow certain doctors to legally prescribe herion and b) invest huge amounts of money in literacy programmes to identify and treat dyslexia. Seeing as the *vast* majority of prisoners are either heroin addicts and/or suffer from dyslexia, I'd suggest it would be more cost-effective than cutting a hand or two off.
Anyway, we'd have to pay disability benefit to the amputees!