Legalized abortion and crime effect
The effect of legalized abortion on crime (sometimes referred to as the Donohue-Levitt hypothesis) is the theory that legal abortion reduces crime. Proponents of the theory generally argue that children who are unwanted or whose parents cannot care for them well are more likely to become criminals and that an inverse correlation is observed between the availability of abortion and subsequent crime. Moreover, children born under these conditions are usually economically disadvantaged. In particular, it is argued that the legalization of abortion in the United States, largely due to the Supreme Court's decision in Roe v. Wade, has reduced crime in the late 20th and early 21st centuries. Opponents generally reject these statistics, and argue that abortion has negative effects on society or decrease in crime is brought about in other ways.
1972 Rockefeller Commission on Population and the American Future
The 1972 Rockefeller Commission on Population and the American Future is one of the better known early versions of this claim, although it was not the first. The Commission cited research stating that the children of women denied an abortion "turned out to have been registered more often with psychiatric services, engaged in more antisocial and criminal behavior, and have been more dependent on public assistance." A 1966 study by Hans Forssman and Inga Thuwe was cited by the Rockefeller Commission and is probably the first serious empirical research on this topic. They studied the children of 188 women who were denied abortions from 1939 to 1941 at the hospital in Gothenburg, Sweden. They compared these unwanted children to another group – the next child born after each of the unwanted children at the hospital. The unwanted children were more likely to grow up in adverse conditions, such as having divorced parents or being raised in foster homes and were more likely to become delinquents and engaged in crime. Supreme Court Justice Blackmun's opinion in Roe v. Wade also referenced the social and private problems "of bringing a child into a family already unable, psychologically and otherwise, to care for it."
Donohue and Levitt study
Steven Levitt of the University of Chicago and John Donohue of Yale University revived discussion of this claim with their 2001 paper "The Impact of Legalized Abortion on Crime". Donohue and Levitt point to the fact that males aged 18 to 24 are most likely to commit crimes. Data indicates that crime in the United States started to decline in 1992. Donohue and Levitt suggest that the absence of unwanted children, following legalization in 1973, led to a reduction in crime 18 years later, starting in 1992 and dropping sharply in 1995. These would have been the peak crime-committing years of the unborn children.
The authors argue that states that had abortion legalized earlier should have the earliest reductions in crime. Donohue and Levitt's study indicates that this indeed has happened: Alaska, California, Hawaii, New York, Oregon and Washington experienced steeper drops in crime, and had legalized abortion before Roe v. Wade. Further, states with a high abortion rate have experienced a greater reduction in crime, when corrected for factors like average income. Finally, studies in Canada and Australia claim to have established a correlation between legalized abortion and overall crime reduction.
The study was criticized by various authors, including a 2001 article by John Lott and John Whitley where they argued that Donohue and Levitt assume that states which completely legalized abortion had higher abortion rates than states where abortion was only legal under certain conditions (many states allowed abortion only under certain conditions prior to Roe) and that CDC statistics do not substantiate this claim. In addition, if abortion rates cause crime rates to fall, crime rates should start to fall among the youngest people first and then gradually be seen lowering the crime rate for older and older people. In fact, they argue, the murder rates first start to fall among the oldest criminals and then the next oldest criminals and so on until it last falls among the youngest individuals. Lott and Whitley argue that if Donohue and Levitt are right that 80 percent of the drop in murder rates during the 1990s is due solely to the legalization of abortion, their results should be seen in some graphs without anything being controlled for, and that in fact the opposite is true. In addition, Lott and Whitley pointed out that using arrest rate data to proxy crime rates is flawed because arrest for murder can take place many months or even years after the crime occurred. Lott and Whitley claim that using the Supplemental Homicide Report, which links murder data for when the crime occurred with later arrest rate data, reverses Donohue and Levitt's regression results.
In 2005 Levitt published a rebuttal to these criticisms in which he re-ran his numbers to address the shortcomings and variables missing from the original study. The new results are nearly identical to those of the original study. Levitt posits that any reasonable use of the data available reinforces the results of the original 2001 paper.
Later in 2005, Christopher Foote and Christopher Goetz claimed that a computer error in Levitt and Donahue's statistical analysis led to an artificially inflated relationship between legalized abortion and crime reduction. Once other crime-associated factors were properly controlled for, they claimed that the effect of abortion on arrests was reduced by about half. Foote and Goetz also criticize Levitt and Donahue's use of arrest totals rather than arrests per capita, which takes population size into account. Using Census Bureau population estimates, Foote and Goetz repeated the analysis using arrest rates in place of simple arrest totals, and found that the effect of abortion disappeared entirely.
Donohue and Levitt subsequently published a response to the Foote and Goetz paper. The response acknowledged the mistake, but showed that with different methodology, the effect of legalized abortion on crime rates still existed. Foote and Goetz, however, soon produced a rebuttal of their own and showed that even after analyzing the data using the methods that Levitt and Donohue recommend, the data does not show a positive correlation between abortion rates and crime rates.  They are quick to point out that this does not necessarily disprove Levitt's thesis, however, and emphasize that with data this messy and incomplete, it is in all likelihood not even possible to prove or disprove Donohue and Levitt's conclusion.
A 2007 study by Jessica Reyes at Amherst College stated: "By the year 2020, when the effects of the Clean Air Act and Roe v. Wade would be complete, violent crime could be as much as 70% lower than it would be if lead had remained in gasoline, and as much as 35-45% lower than it would be if abortion had never been legalized. At the same time, history suggests that other unknown factors would have increased crime by perhaps 3-5% per year."
- Freakonomics by Levitt and Stephen J. Dubner; Chapter 4 discusses this effect.
- Freedomnomics by John Lott; Chapter 4 discusses this effect.
- Statistical correlations of criminal behaviour
- Roe effect
- Title X
- Unintended pregnancy
- Rockefeller Commission on Population and the American Future
- Hans Forssman and Inga Thuwe, "One hundred and twenty children born after application for therapeutic abortion refused," Acta Psychiatrica Scandinavica, 1966, 71–78
- Roe v. Wade (No. 70-18) 314 F.Supp. 1217
- Freakonomics, Chapter 4, Where Did All the Criminals Go?
- John R. Lott Jr. and John E. Whitley, "Abortion and Crime: Unwanted Children and Out-of-Wedlock Births", (2001) SSRN Yale Law & Economics Research Paper No. 254 working paper and Economic Inquiry, Vol. 45, No. 2, pp. 304-324, April 2007 published article.
- Abortion and crime: who should you believe?
- "Measurement Error, Legalized Abortion, the Decline in Crime: A Response to Foote and Goetz (2005)", Donohue and Levitt, 2006
- Christopher L. Foote & Christopher F. Goetz (2008-01-31). "The Impact of Legalized Abortion on Crime: Comment" (PDF). Federal Reserve Bank of Boston. Retrieved 2008-05-12.
- Environmental Policy as Social Policy? The Impact of Childhood Lead Exposure on Crime, Reyes, Jessica Wolpaw, The B.E. Journal of Economic Analysis & Policy, Volume 7, Issue 1, page 34.
- Charles, Kerwin Ko., and Melvin Stephens, Jr. 2002. "Abortion Legalization and Adolescent Substance Abuse." NBER Working paper No. 9193.
- Leigh, Andrew, and Justin Wolfers, "Abortion and Crime," AQ: Journal of Contemporary Analysis 2000, 72(4), pp. 28–30.
- Pop-Eleches, Christian. 2003. "The Impact of an Abortion Ban on Socio-Economic Outcomes of Children: Evidence from Romania." Harvard University Department of Economics. Unpublished.
- Sen, Anindya. 2002. "Does Increased Abortion Lead to Lower Crime? Evaluating the Relationship between Crime, Abortion, and Fertility." University of Waterloo Department of Economics. Unpublished.
- Sorenson, Susan, Douglas Wiebe, and Richard Berk, "Legalized Abortion and the Homicide of Young Children: An Empirical Investigation," Analyses of Social Issues and Public Policy 2002, 2(1), pp. 239–56.
- John D. Mueller, "Dismal Science" Claremont Review of Books, Spring 2006
- Donohue and Levitt, "The Impact of Legalized Abortion on Crime" (PDF) Quarterly Journal of Economics, May 2001.
- Josh Wright, "A Brief Primer on the Abortion and Crime Debate"