Without the threat of prison there is no meaningful deterrent to a life of petty theft. If the system isn't going to do anything why not just keep stealing?
There is so much wrong in these two sentences that it's hard to know where to start.
Imprisonment is not the only thing that anyone could possibly feel threatened by.
The threat of prison is currently NOT a meaningful deterrent to a life of petty theft, because deterrence depends on a risk assessment, and risk is consequence multiplied by probability - and petty thieves consider the probability of being caught to be close to zero. No matter how severe they consider imprisonment to be as a consequence, any number multiplied by a very tiny number yields a very tiny number.
The system currently isn't going to do anything. Seriously. Call the cops as the victim of a petty theft, and watch as the justice system leaps into action - oh, wait, I mean watch as the only action taken is to give you a police report number so that you can make an insurance claim.
No matter how harsh you make the punishments, no petty criminal will be deterred by them in a system where he expects never to be punished at all.
However, the evidence from elsewhere strongly suggests that non-custodial punishments are highly effective in deterring crime,
as long as there's a high probability that any crime will lead to such a punishment.
The evidence based approach to reducing petty crime is:
- Small penalties
- Penalties that don't reduce the future ability of offenders to find lawful employment
- High probability of detection
- High probability of conviction for guilty suspects
- Low probability of conviction for innocent suspects
- Short delay between crime and trial
- Short delay between conviction and sentencing
- Mutual respect and trust between police and community
- Uniform application of the law to all citizens
- Punishments that are proportionate to the harm done by the offender
- Equal punishment for equal crimes
The system in most parts of the USA is almost as poorly designed to meet these requirements as it could be; And yet the proposed "solution", of further increasing the length of prison sentences, is one of the few ways in which it could actually be made worse.
The money currently being wasted on prisons could and should be being spent on detection, investigation, and forensics to ensure that petty criminals are likely to be caught; On the court system to ensure that trials are both timely and equitable; And on community policing to engage police and other citizens with each other, and build trust and friendship between officers and the public at large.
But most of all, if the objective is lower incidence of petty crime, that money should be spent on education, employment programs, housing programs, and a social safety net.