The justice system needs to take rape more seriously. That doesn’t mean longer prison sentences.

Progressives want to eliminate rape culture and mass incarceration. Those goals don’t have to be in conflict.

Earlier this year, a college student’s prison sentence triggered nationwide outrage — former Stanford University student Brock Turner was sentenced to a measly six months in jail after he sexually assaulted an unconscious woman. The outcry was so widespread that it inspired California legislators to pass a bill this week that would require at least three years in prison for those convicted of sexual assault against an unconscious or intoxicated person.

The bill, which still needs Gov. Jerry Brown’s signature to become law, was widely praised by some progressive leaders in the state, who have long demanded that the criminal justice system take sexual assault and rape much more seriously than it does today. Eliminating a judge’s discretion and requiring at least three years in prison, some advocates argue, accomplishes that.

But is a longer prison sentence really the right approach to getting this issue taken more seriously?

There’s no doubt the criminal justice system has long neglected sexual assault and rape. Nationally, according to the Rape, Abuse, and Incest National Network (RAINN), for every 1,000 rapes, 993 will go unpunished.

An example came from one of the many troubling findings in the Justice Department’s investigation of the Baltimore Police Department: One problem federal investigators uncovered is the department didn’t take sexual assault allegations seriously, with an officer describing one victim as “a conniving little whore” and one detective allegedly claiming that “all our cases are bullshit.”

This is a problem. Because it’s such a serious problem, finding real solutions is urgent and needed. But that doesn’t mean that anything that looks tougher, such as longer prison sentences, is the right idea.

In fact, there’s a real concern that extending or mandating prison sentences will conflict with another progressive priority: ending mass incarceration, a policy that turned America into the world’s leader in incarceration.

Some historical context is important here: Although mass incarceration has often been framed as a result of the war on drugs, it’s in fact mostly driven by harsh prison sentences for all crimes and particularly violent offenses.

The statistics bear this out: Drug offenses are indeed a significant contributor, making up about 21 percent of the jail and prison population. But the most common offenses are violent crimes, which nearly 40 percent of the prison population is in for.

So ending mass incarceration will require more leniency on the end of violent offenses. Creating longer prison sentences for sexual assault goes against that objective. What’s more, it could actually fail to solve these problems: The criminal justice research shows what matters is not the harshness of the punishment, but the certainty that someone will be punished once they offend. That means focusing on what prosecutors and the police are doing to punish more sex offenders — not putting some of these offenders in prison for longer.

America got to mass incarceration by wanting to punish the crimes of the day harshly

Let’s back up first. To understand how California’s bill relates to mass incarceration, it’s important to understand the mentality that people approached crime policy with back in the 1960s through 1990s, and how that mentality persists, with crimes like rape and sexual assault, today.

Back in the 1960s through 1980s, violent crime rates rose dramatically. According to FBI statistics, the murder rate — a relatively reliable proxy for violent crime — went from from 5.1 per 100,000 people in 1960 to 10.2 in 1980. It remained around that level until the mid-1990s, and since then it has dropped down to 4.5 in 2013 and 2014.

But it wasn’t just murder. It was robbery. It was assault. It was rape. All of these crimes went up, and Americans were terrified. Criminologist Barry Latzer cited a federal study in his book, The Rise and Fall of Violent Crime in America, that encapsulated the reason for concern:

The federal Bureau of Justice Statistics once calculated, based on crime victimization rates from 1975 to 1984, the lifetime chances of being raped, robbed, or assaulted. The numbers were astounding. If crime rates remained the same (which, of course, they didn’t), 83 percent of all Americans aged 12 at the time would, in their actuarial lifetimes, be victimized by an attempted or completed violent crime, and 40 percent would be injured as a result of a robbery or assault.

This is what the public, politicians, and media were seriously worried about back in the 1980s and 1990s. Rates of violent crime and drug use, particularly during the crack cocaine epidemic of the 1980s, really were unusually high, as federal statistics show. And the public knew it: Gallup’s polling shows Americans in the 1960s, 1970s, 1980s, and especially the early 1990s (likely due to the crack cocaine epidemic) were much more likely to say that crime was "the most important problem" facing the US.

In response, all levels of government escalated prison sentences for almost all crimes — not just drug offenses, but violent ones, too.

A 2014 report by the National Research Council demonstrates this: Although the average length of prison sentences for drug offenses barely increased from the 1980s to the 2000s, the average length of prison sentences for violent offenses like murder and sexual assault dramatically increased.

National Research Council

The result: The incarceration rate went from 100 per 100,000 people in the 1970s to nearly 700 by the 2000s — a rate higher than any other country in the world save the tiny African nation of Seychelles. In comparison, the United Kingdom, France, Germany, and Canada’s incarceration rates are all below 150.

But since so much of the prison population is in for violent crimes, getting America’s incarceration rates back to these other countries’ levels will require pulling back the punishment of violent offenders, as this great interactive from the Marshall Project demonstrates:

All of this is to contextualize the rationality of mass incarceration: There was a serious rise in violent crime, and people were genuinely worried about it. Politicians responded by making the entire criminal justice system more punitive. And it wasn’t just about drugs; it was about very serious crimes that virtually everyone agrees we should all be worried about.

But the policies still led to the high cost of prisons — up to $80 billion each year, according to the Hamilton Project — and huge racial disparities in incarceration — with black people nearly six times as likely to be locked up as their white peers (and only 61 to 80 percent of that overrepresentation explained by higher crime rates in black communities).

Americans, including progressives, are doing the same thing today. We are worried about rape. We are worried about the opioid painkiller and heroin epidemic. We are worried about gun violence. We are worried about hate crimes against minorities and LGBTQ people. And we very much should be — these are all serious problems involving a lot of hurt, even death.

The problem comes in how we respond to these worries. California’s sexual assault bill would continue the trend of stepping up incarceration in response to crime concerns. Americans support hate crime legislation that adds long prison sentences to crimes that are already heavily punished. Prosecutors are charging people with murder charges because they deal opioids. Chicago officials want longer prison sentences for violent offenders involved in shootings.

If you’re worried about the financial and human rights costs of mass incarceration, this recent trend should worry you — especially since much of the criminological evidence goes against mass incarceration.

The justice system should take rape and hate crimes seriously. It can do that without more incarceration.

Justin Sullivan/Getty Images

It would be one thing if we knew that mass incarceration and harsh prison sentences are a good way to fight crime. The truth, based on centuries of research, is they’re not.

One of the most common responses I get to these types of stories is something along the lines of, “Why are you worried about how long a rapist or murderer is locked up? I feel no sympathy for him!” But I’m not worried about that one individual either.

Here’s what worries me: Mass incarceration has cost the US an enormous amount — again, up to $80 billion a year. And it has cost all of this without putting a significant dent in crime in recent decades: According to a 2015 review of the research by the Brennan Center for Justice, more incarceration at best explained 0 to 7 percent of the crime drop since the 1990s.

The study of crime offers an explanation for why. In criminology, the three levers for fighting crime, as criminal justice expert Mark Kleiman previously explained, are the swiftness, certainty, and severity of punishment — established way back in the 1700s by an Italian criminologist called Cesare Beccaria.

When we talk about increasing the length of prison sentences, we’re talking about the severity of punishment. This has been the lever that public policy has largely relied on over the past few decades, leading to the buildup of mass incarceration.

But severity is, based on the available evidence, the weakest of these levers. What criminologists have found is that the certainty of punishment is far more important.

A 2010 review of the research by the Sentencing Project supported this. It pointed to a study by the Institute of Criminology at Cambridge University in 1999 that concluded that “the studies reviewed do not provide a basis for inferring that increasing the severity of sentences generally is capable of enhancing deterrent effects,” and that macro-level studies reviewed by the researchers found that an increased likelihood of apprehension and punishment — certainty — was linked to falling crime rates.

The US National Institute of Justice agrees, writing earlier this year, “Research shows clearly that the chance of being caught is a vastly more effective deterrent than even draconian punishment.” They added, “Research has found evidence that prison can exacerbate, not reduce, recidivism. Prisons themselves may be schools for learning to commit crimes.” So more certainty of punishment can deter crime, while more severity can actually make it worse after a certain point.

To some degree, this is common sense: People tend to commit crimes thinking they’ll get away with them, so whether they’re punished by 10, 20, or 100 years in prison is really not very important. But if you change their notions that they can get away with crime by making it more likely the criminal justice will punish them, then you can make an impact.

Kleiman explained:

Why do some people keep committing crimes, to their own evident disadvantage? Because they’re present-oriented and impulsive, with deficient capacities for shaping their current behavior in light of their future goals, and with poor judgment about their actual odds of getting caught: all characteristics, as noted above, likely to be produced by growing up in high-crime neighborhoods. (Neglectful and abusive parenting also contributes, of course. So does exposure to environmental lead[.])

All of that should make it clear enough: Certainty truly matters for fighting crime, but severity is relatively weak.

So what does all of this have to do with sexual assault and other serious offenses progressives are worried about?

Well, the issue with these crimes is not that people are punished too leniently once they get caught. It’s that people don’t seem to get caught and punished at all.

As RAINN’s statistics on sexual assault show, out of every 1,000 rapes, 993 will go unpunished. Only about a third — 344 — are reported to police, 63 of those reports lead to arrest, 13 of those cases are referred to prosecutors, seven of those cases lead to a felony conviction, and just six of those rapists will be incarcerated. In comparison, for every 1,000 assault and battery crimes, 41 lead to a felony conviction and 33 lead to incarceration — still relatively low rates, but much higher than sexual assault rates.

So the problem is that way too many rapists can get away with their crime. There is simply no certainty that they’ll get caught, which makes the deterrent effects of a very severe punishment next to negligible. (Of course, there is a value to some severity to incapacitate serial rapists. So there’s a balancing act here.)

One big reason for the low conviction rates, as Dara Lind reported for Vox, is police and prosecutors simply don’t take rape allegations seriously enough:

Police have historically thought that false rape allegations are much more common than they actually are. (One study of the Philadelphia Police Department from the 1960s found that officers thought that 75 to 90 percent of rape claims were false; the actual proportion found in the study was, at most, 21 percent.) So it makes sense that they're going to be skeptical of each individual allegation. But this is self-perpetuating: the more common an officer thinks false rape claims are, the more likely he is to be skeptical of each new allegation; the more likely he is to conclude that the allegation is false; the higher the numbers of false allegations will be.

Because of this, some sexual assault advocates argue that California’s bill misses the mark. As SurvJustice founder and Executive Director Laura Dunn told NBC News, “You may set mandatory minimums, but you're forgetting there's prosecutorial discretion, police discretion before it even gets to a jury decision.”

Now this is an area where lawmakers can be more effective in adjusting the criminal justice system. They can, for example, boost funding to police, prosecutors, and other actors in the criminal justice system on the requirement that they take these crimes more seriously. So perhaps these actors can set up a sex crimes division, which focuses solely on sexual assault cases, and provide funds for the training and oversight required to make this work.

These are the kinds of steps the Violence Against Women Act took when Congress moved to take sexual assault more seriously. The legislation also came with more stringent prison sentences, but there’s no reason to believe that part is necessarily required — as the research on certainty versus severity of punishment demonstrates.

In fact, the severity of prison time could be lessened if certainty is increased enough. For studies in South Dakota, RAND Corporation researchers looked at a program that put alcohol offenders, such as drunk drivers, under a very strict probation period. As part of this probation, these offenders had to take a twice-a-day alcohol test. And if they failed, they had to spend a night or two in jail — a certain but pretty mild punishment.

The result: Researchers linked the program to a 4.2 percent decrease in average adult mortality rates, a 12 percent reduction in repeat DUI arrests, and a 9 percent reduction in domestic violence arrests at the county level in South Dakota. These are big drops — and they were achieved with a relatively mild threat of a couple days in jail.

Similar interventions had similar success, like the HOPE Probation program in Hawaii for drug offenders. If these types of interventions are implemented correctly, lawmakers could, potentially, reduce prison sentences — and pull back mass incarceration — while maintaining the deterrent effects of the criminal justice system.

Crime is a tough issue, one that is often tangled with anger and grief over some of the most vile acts humans are capable of. But the biggest concern with the criminal justice system is making public policy for fighting crime effective at, well, fighting crime. The research shows longer prison sentences aren’t the right path — and, crucially, locking people up for longer could clash with the important task of ending mass incarceration.