Here's the abstract to Ted Joyce's unpublished new paper:
The inverse relationship between abortion and crime has spurred new research and much controversy. If the relationship is causal, then polices that increased abortion have generated enormous external benefits from reduced crime. In previous papers, I argued that evidence for a casual relationship is weak and incomplete. In this paper, I conduct a number of new analyses intended to address [Levitt and Donohue's] criticisms of my earlier work.
First, I examine closely the effects of changes in abortion rates between 1971 and 1974. Changes in abortion rates during this period were dramatic, varied widely by state, had a demonstrable effect on fertility, and were more plausibly exogenous than changes in the late 1970s and early 1980s. If abortion reduced crime, crime should have fallen sharply as these post-legalization cohorts reached their late teens and early 20s, the peak ages of criminal involvement.
It did not.
Second, I conduct separate estimates for whites and blacks because the effect of legalized abortion on crime should have been much larger for blacks than whites, since the effect of legalization of abortion on the fertility rates of blacks was much larger.
There was little race difference in the reduction in crime.
Finally, I compare changes in homicide rates before and after legalization of abortion, within states, by single year of age. The analysis of older adults is compelling because they were largely unaffected by the crack-cocaine epidemic, which was a potentially important confounding factor in earlier estimates.
These analyses provide little evidence that legalized abortion reduced crime.
Ted Joyce National Bureau of Economic Research and Baruch College, City University of New York
In another unpublished paper, John R. Lott and John Whitley found correlations suggesting that increased abortion actually increased the murder rate.
Previous empirical work linking abortions and crime has assumed, with the exception of five states, that no abortions took place prior to the Roe v. Wade decision in January 1973. In fact, abortion data from the Centers for Disease Control indicate that states which allowed abortions prior to the Roe v. Wade only when the life or health of the mother was in danger actually had higher abortion rates than some states where it was legal. The use of data from the Supplemental Homicide Report also allows the direct linkage between the current age of the murderer and the abortion rate when those murders were born.).
One more abortion per 1,000 females age 15-44 (i.e., about four percent of the average) is associated with between a 0.12 to 0.9 percent increase in murders in any given year. Similar estimates are obtained using abortions per 1,000 live births. Linear estimates indicate increased annual victimization costs by at least $3.2 billion.