What sentence is a crime worth?

Usually, this question is answered in terms of months and years, but in Philadelphia, prosecutors must now also add up dollars and cents. That's because District Attorney Larry Krasner has directed all of his prosecutors to state on the record – in every case – how much a recommended sentence would cost taxpayers and to justify it accordingly.

Krasner's willingness to bring much-needed policy innovations to a prosecutor's office is laudable, but cost-conscious prosecution needs to be pursued carefully and should not exclude other important sentencing considerations.

Krasner rightly highlights the need to address costs in our criminal justice system. As a nation, we spend around $80 billion each year incarcerating individuals in our prisons and jails. Pennsylvania spends more than $2 billion on its prisons alone. As Krasner notes in his memo to prosecutors, the $42,000-per-year cost to imprison a single person in the state approaches the starting salaries for many public safety and education professionals. And, of course, these numbers do not even begin to touch the impact that a loss of freedom has on the individual serving a sentence, or how it ripples out to affect his family and community.

Given the staggering financial and human costs of incarceration, the appeal of Krasner's policy is clear. There is a real need to adopt policies that help reduce our over-incarceration problem. The District Attorney's Office, with its broad discretion over sentencing recommendations, ought to be included in that discussion.

However, enumerating average costs alone is insufficient prosecutorial participation.

As large as incarceration expenditures loom, there are real dangers to giving prosecutors only one piece of a much larger sentencing puzzle. At least as important as sentencing costs are the success rates of sentencing options – for example, how often individuals reoffend after completing a sentence. Other facts and figures may not be as easily tallied but are no less relevant. What about the savings of a crime prevented or trauma avoided? Having prosecutors highlight and justify the average price tag of a given sentence attaches too much significance to these numbers and ignores the other half of the cost-benefit equation.

Fiscal responsibility should not come at the expense of the individual's needs and community safety. If an individual is truly a public safety risk, and incarceration is truly the best option, the cost should not be used to induce the prosecutor to avoid such a recommendation. If a young person would be best served by the juvenile justice system, even though services are more expensive there, that young person should remain in the juvenile system. And if an individual has drug abuse issues and needs to be held in a treatment center that is pricier than prison, cost shouldn't prevent the individual from receiving such treatment. In short, cost cannot be the be-all and end-all of governmental policy.

Further, applying averages and statewide statistics to individual defendants can be highly unreliable and inaccurate because of the massive variation that can occur within a group. The simple fact that a given sentencing option has a certain overall rate of reoffending or an average cost of implementation doesn't mean that those numbers will bear any resemblance to the actual potential success or cost for any given defendant. Asking line prosecutors to read out averages that don't accurately represent the particular case could do more harm than good.

The potential for these statistics to have undue and ill-applied weight is further exacerbated by the conditions found in most courtrooms. Prosecutors and their defense counterparts are notoriously overworked and short on time. No matter how earnestly they approach cost considerations, they simply do not have the bandwidth, not to mention the mathematical training, to accurately tailor statistics to individual cases. Additionally, reading out a cost estimate in each case is likely to become rote, like so many other features of plea bargaining and the sentencing process, and will likely become meaningless over time.

The burden of cost-conscious prosecution is best assumed by the senior leadership of the District Attorney's Office. These officials could allow the data to shape department-wide sentencing guidelines in a manner that places downward pressure on sentences and incentivizes the use of less-restrictive options without jeopardizing individualized sentencing or forcing line prosecutors to make what are essentially state budget decisions.

Krasner's innovative, reform-minded approach to criminal justice is a move in the right direction. He has fired those opposed to reform, published lists of bad cops, and opposed cash bail. And he is right to remind his prosecutors of the incredible costs associated with sentencing. However, Krasner's most recent directive could ultimately frustrate what he is trying to accomplish by subverting justice instead of promoting it.

Lars Trautman and Nila Bala are senior fellows with the R Street Institute. Trautman is a former assistant district attorney and Bala is a former public defender.