Marijuana Possession and Incarceration Cross-Post

Photo Credit: Hossam el-Hamalawy

I was over at the Reality Based Community, as I often am when I'm not here, when I got into an interesting discussion about the nationwide prison population. The big news from Keith Humphrey's original post is that 2010 saw the largest decline in the prison population in the last 40 years. Actually, it was the only decline in the prison population in the last 40 years. It had been on a steady upward trajectory for the last four decades. So what happened?

Mr. Humphreys credits some changes in federal policy:

The president’s administration would have to roll back the crack/powder cocaine sentencing disparity and end “drug war” rhetoric, creating change at the federal level and also inspiring individual states to re-evaluate their drug sentencing guidelines. The Administration would also have to invest in re-entry programs and highlight more effective methods of parole and probation. Marijuana possession cases make far less contribution to incarceration than Gopnik asserts in his article, but some marginal reductions in the number of people under criminal supervision could come from a White House reversing past practice and not opposing state-level marijuana decriminalization laws in places such as California and Massachusetts.

I should mention that Mr. Humphreys is referring to this Gopnik article which I have not read. I latched on to the question of whether incarceration can seriously be linked to marijuana possession cases per se:

Out of curiosity, does the number you’re looking at include incarcerations resulting from parole violations where the original contact with the courts was for a marijuana offense? I would assume that the vast majority of marijuana cases do not land people in jails for a long time, but subsequent contact with police and courts would create an outsized effect on incarceration. I imagine this could become difficult to investigate.

My impression is that first-time marijuana possession cases, even if they result in a conviction, rarely result in actual incarceration. Community service, a fine, time-served, etc... seem like more common outcomes, but I don't know; I'm not a political scientist that researches the criminal justice system. Basically, what I was trying to articulate was:

Say there's a case where someone gets arrested and brought before a judge for marijuana possession. Defendant pleads guilty, and is sentenced to probation. Six months later, defendant violates probation with a non-drug offense, and is incarcerated.

The probation results from marijuana possession, and the incarceration results from the probation, but I doubt that whatever statistics that exist on incarceration would link the incarceration to marijuana possession. The effect of having marijuana possession as illegal in many states boosts overall incarceration rates without a direct trace to "incarcerations due to marijuana possession" in the statistics.

We are seeing a drop in the number of state convictions for marijuana possession as many states and municipalities have instructed their police forces to avoid making marijuana arrests a priority. Fewer marijuana possession cases are going before judges, resulting fewer and fewer probation sentences and incarceration. It might be possible to separate out the effect on decriminalization of marijuana on the size of the population in a state that is subject to supervision by courts, parole officers, and treatment programs.

Mr. Humphreys seemed to be pointing in a different direction. Assume a different case in which a convict is on parole (or probation), but violates the terms of the agreement by failing a drug test. This is separable from 'marijuana possession' in two important ways: a failed drug test is not "possession" from a criminal law standpoint, and even if a state decriminalizes marijuana, that democratic consensus doesn't control whether 'clean drug tests' make up a part of a parole or probation agreement. Parolees can still be incarcerated for marijuana use in states in which decriminalization and use are not pursued by police and rarely prosecuted:

That is exactly what I was thinking of. Simple MJ possession will not land anyone outside the system in a state or federal prison –it’s very hard to get even one night in jail (IIRC Peter Reuter estimates that there is one MJ arrest for every 10,000 joints smoked in the US and one incarceration for every 3 million joints smoked in the US). Federal prosecutors will not even take a case these days for MJ unless someone has 10-1000 pounds of MJ. But if you are in the criminal justice system already, e.g., on parole/probation, MJ puts you at more risk of getting put back inside, depending on what your PO drug tests for and how s/he reacts to a positive test.

I was imagining a different causal arrow, in which marijuana brings people into the system. Mr. Humphreys points out that the more likely scenario that would increase incarceration is one in which parolees are re-incarcerated due to marijuana-related policy.

The first case is amenable to democratic processes; the latter is more of an administrative matter, and leadership from the White House's crime control and probation policy people seem to be making inroads in bringing down the incarceration rates where they can. I would imagine that those changes are dwarfing any effect of decriminalization on incarceration rates.