At the vanguard of an emerging field called household economics, Wolfers, an assistant professor of political economy at the Stanford Graduate School of Business, used microeconometric techniques. He and Stevenson weighed the changes in the bargaining threat point: Like workers and employers, a husband and wife can produce more together than separately. In labor markets, workers demand a certain share of the joint product or they exercise their options to go elsewhere. In marriage, "a husband and wife can each threaten the other implicitly if each has outside options," Wolfers said.
No-fault divorce laws allow one person to dissolve a marriage without the consent of the spouse. In most states before no-fault, divorce required consent of both or proof of fault by the non-consenting spouse. "Under no-fault wives can always threaten to walk out without the husband's permission, changing the power balance in the relationship," Wolfers said. The husband, understanding the lowered threat point, behaves himself, thereby reducing the incidence of domestic violence and spousal homicide -- and increasing women's wellbeing, he argues.
Because states changed their divorce laws at different times, the researchers could examine the impact in state-by-state comparisons. For example: California changed its law in 1969, Massachusetts in 1975. "If we expect the suicide rate to fall, we expect it to fall six years earlier in California than in Massachusetts," said Wolfers.
Tapping into the national database of death certificates, Wolfers and Stevenson traced suicide rates before and after divorce reform and found a statistically significant reduction of nearly 6 percent in the female suicide rate following a state's change to unilateral divorce. There was no discernible change in male suicides. Looking longer term, they found close to a 20 percent decline in female suicides 20 years after the change to no-fault divorce.
The researchers then turned to national crime data and family violence surveys that were conducted in 1976 and 1985 by sociologists Murray Straus and Richard Gelles. Wolfers and Stevenson found that domestic violence against women declined from the first survey to the second in the states that had adopted no-fault divorce laws between 1969 and 1983, whereas it had increased in nine states that either had historically had unilateral divorce or had never enacted the reform. The percentage of husbands abused by their wives increased in the 11 states with unchanged laws also, yet remained the same in no-fault divorce states. For women, the change was greatest: Women victims of spousal violence declined by 1.7 percent from 12.8 percent in the reform states in the same period that spousal violence against women increased 2.5 percentage points in the non-reform states.
Wolfers and Stevenson also looked at FBI Uniform Crime Reports for trends on spousal homicide. Reporting definitions of relationships changed, making the data comparisons difficult, but the available evidence points to a decline in females murdered by their partners in no-fault divorce states, with no discernible effects for men murdered.
Critics of no-fault divorce have argued that it leads to the breakdown of the family unit. In a separate study, Wolfers found that while divorce rates rose sharply immediately after a state adopted no-fault divorce laws, the trend reversed within about a decade. He chalks up the initial spike to pent-up demand for divorce.
Probing deeper, he returns to the labor market analogy. "The main effect of right-to-strike is not that workers strike more; rather, they can now credibly threaten their employer with a strike, and this newfound bargaining power leads to higher wages but not that many more strikes." The same is true for the threat to divorce, he said.
"If you're looking for the 'smoking gun' to explain the decline in the traditional American family, it's not the no-fault divorce laws," Wolfers said. "Rather than looking on them as the cause of family ills, these laws may actually provide a safety valve for the pressures of family life."