Abortion crime controversy update

Steven Levitt and John Donohue write:

More than two decades have passed since we published an academic paper linking the legalisation of abortion to the enormous decline in American crime since the 1990s. The underlying theory is straightforward. Children who are unwanted at birth are at risk of a range of adverse life outcomes and commit much more crime later in life. Legalised abortion greatly reduced the number of unwanted births. Consequently, legalised abortion will reduce crime, albeit with substantial lags. . . .

The data available at the time strongly supported our hypothesis. We showed, for instance, that crime began falling sooner in the five states that legalised abortion in advance of Roe v Wade, . . . crime in states with high and low abortion rates followed nearly identical trends for many years, then suddenly and persistently diverged only after the birth cohorts exposed to legal abortion reached the age at which they would commit crime. . . . looking at arrest data, which reveal the age of the offender, the declines in crime were concentrated among those born after abortion became legal.

These data patterns do not, of course, make an open-and-shut case. No randomised experiment has been conducted on this topic. We also didn’t help our own case by mislabelling the set of control variables included in one of the specifications in one of our tables—a regrettable mistake (later corrected) which led some people to dismiss all of the paper’s findings. . . . We concede that reasonable people could disagree about how convincing the findings were in our initial paper.

They now come in with new data:

We could already at the time of our first academic paper in 2001 make strong predictions about what our theory would predict should happen to future crime. Indeed, at the end of that paper, we made the following prediction: “When a steady state is reached roughly 20 years from now, the impact of abortion will be roughly twice as great as the impact felt so far. Our results suggest that all else equal, legalised abortion will account for persistent declines of 1% a year in crime over the next two decades.” . . .

That’s what we did in a paper published in 2020. Our methodological approach was straightforward: mimic the specifications reported in our original paper, but limit the time period to the years that were out of sample, ie, those after our original data ended.

The results provided stunning corroboration of our predictions. For each of the seven different analyses we had presented in the initial 2001 paper, the results for next two decades of data were at least as strong as the results in our initial dataset, and in most specifications even stronger. This included what the main critics of our 2001 paper called the “crucial” test, showing that the abortion rate at the time of any birth cohort negatively correlated with the age-specific arrest rate for that cohort years later as it moved through ages 15–24, while perfectly controlling for whatever other factors were influencing crime in a given state and a given year.

The magnitude of the implied impacts we are talking about is huge. If you look over the entire sample, violent-crime rates fell by 62.2 percentage points in high-abortion states whereas they rose by 3.1% in low-abortion states.

I think they meant to say 62% and 3% here, but I get the point.

Levitt and Donohue continue:

Though there is not complete acceptance of our hypothesis among academics, all agree that if our paper is not correct, then there is no viable explanation for the enormous drop in crime in America that started in the early 1990s. Indeed, there is not even an arguable theory to supplant the abortion-crime link. . . .

I haven’t followed the details on this one, but I was struck by that last quote, so I sent a message to Donohue asking about it. It’s not clear why we should expect a single explanation for the drop in crime. There are lots of social trends that occur without a single clear explanation, right?

Donohue replied:

This may be a semantic disagreement, but what I meant to say was that “no existing explanation for the large, otherwise-unexplained portion of the crime drop has any empirical support at anything close to the abortion/crime hypothesis.” If someone said “I think social trends that influenced the high-abortion states more powerfully is what explained the crime drop,” I would say that could certainly be true, but that is not really a theory but just a conjecture that then would need explaining. But I could imagine that high abortion states were more progressive, and started doing things like pre-school enrichment or better social programs or better policing that reduced crime—but our data shows that whatever happened in these states did emerge in a particular pattern that isn’t simply “high abortion states—perhaps being more progressive—started reducing crime more effectively.”

That’s because our data allowed us to link actual abortion rates in a particular state in say 1980 with crime by 15 year olds in 1995 and compare what was happening to slightly older cohorts in the same state who had been born with lower abortion rates. I think our Table 7 column 2 (showing impact of abortion on violent crime per capita) is perhaps the most unassailable (it is what our critics in 2000 called the “crucial test” of the hypothesis). It essentially looks at crime by 15-24 year olds by single year of age to see their violent crime rates—while controlling for whatever else influences crime in that state in each year of our data. We show that if 15 year olds were born in a cohort that experienced a higher abortion rate than 16 year olds, then the 15 year olds in say Illinois in 1995 would have a bigger drop in crime than the 16 year olds in Illinois (holding constant the fixed effect of crime in Illinois in 1995). The same would then be true the next year (1996) for these same two cohorts who would then be 16 and 17 year olds. Since the 16 year olds had been born in a cohort experiencing higher abortion rates they would still show less violent crime then 17 year olds—and this controls for whatever other factors were influencing crime in the particular state in the particular year.

So yes, other factors could reproduce this effect, but it is not a simple story of some states started doing better at fighting crime and that correlates with higher levels of abortion, since that would not explain the differential effect by year of age (linked back to the abortion rate at the time of the birth cohort).

It still seems to me that there are enough differences between high-abortion and low-abortion states that lots of things could be going on here. In their paper, Donohue and Levitt look at incarceration rates, policing rates, and lead exposure and in his note to me, Donohue mentioned pre-school enrichment or social programs, but I’m not thinking so much about policy as about, yes, what Donohue called “social trends.” We recently discussed similar issues regarding the less politically-contentious topic of the decades-long decline in cigarette smoking. Policy changes can make a difference, but policy changes are also occurring in the context of changes in public opinion and changes in social conditions.

I guess what I’m saying is, yeah, the abortion-crime correlation is worth pointing out and discussing, and I understand Donohue and Levitt’s frustration with critics who don’t seem willing to take yes for an answer; still, what we have here are observational comparisons of trends in different sorts of states.

Dale Lehman send me the following note by criminologists Graham Farrell and Nick Tilley disagreeing with Donohue and Levitt. Farrell and Tilley write:

We support the rights of women to control their fertility. However, we were surprised to see Steven Levitt and John Donohue reiterating their claim that abortion caused a drop in crime. Roe v Wade, the case in 1973 that legalised abortion in America, related only to that country. But the drop in crime was international, occurring in all high-income countries. Abortion was not a factor causing the steep falls in crime observed in Canada, Britain and many other places. Declines in big-volume crimes in America, including burglary and larceny theft, began in 1980 not 1990. This was just seven years after Roe v Wade, so too soon for abortion to have had an impact on adolescent crime.

We have been researching the role of security for many years. Evidence showing the importance of security in generating the reduction in crime has grown.

The Levitt and Donohue analysis relied on five states that introduced abortion earlier than 1973. Any effect is probably spurious and related to income. These states had median incomes far above the national average. Higher-income residents replace their cars and renovate or buy new homes more quickly and frequently, buying more and newer security measures. There is scientific consensus on the effectiveness of electronic vehicle-immobilisers in reducing car theft across multiple jurisdictions, and of door deadlocks in reducing break-ins.

America, followed by other rich countries, experienced what has been termed an avalanche of security in all walks of life. With easy property crimes no longer available, fewer adolescents became involved in crime. This led to reductions in violent crime, which are far fewer in number than property crimes.

There does seem to be a lot more security than there used to be, so I guess this addresses Donohue and Levitt’s claim that “there is no viable explanation for the enormous drop in crime.”