They could stop filling the prisons with 'white collar crime' and non-violent criminals and make more use of public service work as punishment.
Then there'd be more room for the people that should be kept off the streets longer.
Crime should be punished, and dangerous people locked up, but there are a lot of people behind bars who never were a threat to society and could be doing court-required 'volunteer' work instead. That would be more useful to society (and the organizations getting help from these 'volunteers') than feeding and housing them in jail.
Ticks me off to see someone get arrested for killing, raping, or robbing and find out they'd been released from prison after serving, say, 8 years of a 15-year sentence (or something similar) for the same crime previously.
Then some college kid who never got in trouble for anything else gets caught with marijuana and spends 25 years in prison.
Or some shopaholic lady writes a bad check and serves 20 years. Dumb.