Capping Prison Time At Twenty Years Wouldn’t Change Much About Incarceration— The Vast Majority Of Terms Are Much Shorter.

Marc Mauer, executive director of the Sentencing Project, wrote an article in “Democracy” proposing capping prison sentences at twenty years. That may or may not be a good idea, but unfortunately his article doesn’t give a clear picture of the American incarceration experience.

The piece opens with the kind of dramatic anecdote these pieces often open with, about a “college student…with no criminal record…sentenced to three terms of life imprisonment” on drug charges, serving for 20 years before commutation. It calls “stories such as [this] all too familiar”. Stories like this do happen and they’re no less meaningful for being rare, but if they’re “all too familiar” then it’s because they’re the opening dramatic anecdotes to a lot of thinkpieces, not because they’re representative or common.

Roughly speaking, what percentage of prison terms (and the article might say “sentences” but seems to mean continuous prison terms without release or parole) last for twenty years or more? Despite a lot of public attention around incarceration, I suspect this is still a hard question even for most well-informed people.

The reality is that the vast majority of American prison terms — perhaps 80% of them, probably more — last less than five years before release or parole. Most prison terms last less than two years, and I doubt that even 5% last continuously for twenty years or more. I’ll support this more in another article, but it’s not a controversial claim, even though incarceration statistics can be messy and federal numbers might push it up a bit.

Now, looking at the prison population at any given time, instead of at everyone who passes through prison, will give a higher count of such long terms. A great many of the people who serve short prison terms have already been released, and so they’re invisible to the usual, and in my opinion somewhat arbitrary, metrics of “the incarceration rate” and “the [current] prison population”. Far more than 5% of “the prison population” will eventually serve for twenty years or more.

Still, the policy change wouldn’t directly matter for them until they cross year twenty behind bars. And even for however many of the 5% are still in prison, a lot of them will probably serve terms that are just over twenty years, so the effect of a 20-year cap would be pretty marginal — not exoneration, not anything like a short sentence, but a 20 year term instead of a 20–25 year term. That means the effect on “prison population” sizes and “incarceration rates” would be pretty small too, if we have to look at those numbers.

Capping prison terms at twenty years would have a nonexistent or marginal direct effect on nearly everyone who passes through American prisons. That doesn’t make it a bad policy idea (or a good policy idea). You could argue that serving for twenty years instead of twenty-five or thirty years would make an important and worthwhile difference even if it’s for a small number of people, that it would have psychological effects beyond the concrete reduction in time served, or that it could change how prosecutors use threats of long sentences to force plea bargains.

But the “mass” part of “mass incarceration” — the part that seems to affect the largest number of people by far — consists of relatively short prison terms for relatively low-level offenses. I don’t think that’s coming across in the public conversation, and it should.