It seems that many U.S. counties have aging county jails, sometimes poorly maintained and often overcrowded. The "solutions" proposed to such a problem is often to build a larger county jail, or to rent space from another county which has an excess of jail cells and house prisoners in that other county's jail. Sometimes, as is presently the case in Washtenaw County, Michigan, the proposal for a new jail also includes funding for jail alternatives.
I don't doubt that incarceration in a county jail can have a deterrent effect. I don't dispute that, with some individuals, it has a profound rehabilitative effect. But it also seems to me that the population we most wish to deter through the threat of jail is often the least intimidated by its prospect, and the population we least need to deter is the most intimidated.
By way of example, it is not unusual to encounter a first time offender in a criminal law practice who is so mortified and humiliated by an arrest, an overnight in jail, and then being processed through the criminal justice system that you can be pretty sure that they won't reoffend. A hard drinker might quit alcohol after a drunk driving offense. A teenager might see shoplifting in a whole new light when the thoughts of jail and probation overshadow thoughts of college. But at the same time, the guy who protests at the criminal clerk's office that he would rather spend 15 days in jail than pay a $150 fine (something I have in fact witnessed) obviously doesn't share what might be called the traditional middle class perspective on jail.
There is also the belief, both in short-term incarceration and long-term incarceration, that repeat offenders should get progressively longer sentences. Thus, one might see a first time drunk driver get a sentence of probation, a second-time drunk driver spending a month in jail, and a third-time offender spending six months. Unfortunately, I have seen little evidence that the habitual drunk driver is deterred by the prospect of jail - if the first jail sentence doesn't inspire reform, there is a deeper issue at play, perhaps the extent of the defendant's alcoholism, or perhaps the extent to which the defendant's values simply don't align with what the system "expects" of a defendant.
It is interesting to sit through a session of a busy District Court, Michigan's trial court for misdemeanor offenses, on a morning when the arrestees from the night before are being arraigned. Some courts will have the arrestees sit in the jury box as they await arraignment. It is not unusual to see a person among them who looks mortified and traumatized. But it is common to see a significant number of arrestees (ones we might deem "regulars") smiling, laughing, joking, and chatting with each other as if they were waiting for a movie to start. I am simply not convinced that those people are much affected by whether a judge sentences them to ten, twenty, thirty, sixty, or ninety days, or even to six months or a year in jail. They don't want to get caught, but perceive that consequence as "no big deal". With habitual petty criminals, the biggest difference in sentence often seems to be its ultimate cost to the taxpayer.
Frustrations with the effectiveness (or ineffectiveness) of jail have inspired sentencing alternatives, including diversion programs, county work crews (a modern variant of the "chain gang"), "name and shame", and house arrest, and have inspired legislatures to add penalties such as forfeiture or driver's license sanctions onto a variety of offenses. It is not unusual to see a judge or a probation officer express frustration as to how to reach a particular defendant, particularly one who seems to have a lot of potential if only he would stop breaking the law. You may even encounter some people who propose a return to corporal punishment - bringing back public floggings, if not the stocks and pillory. (And you may take note of the "street justice" that some police officers have historically meted out to individuals they deemed unsavory, sometimes with tragic results.)
There do not seem to be any easy answers to this conundrum. But perhaps counties could pool some of the money that might otherwise be spent on longer incarcerations and larger jails, and at least conduct some empirical research into the effectiveness of various sentence lengths and of alternatives to incarceration.