News Release

Same-sex marriage has caused no harms to different-sex couples

New analysis finds that extending marriage rights may have grown support for marriage overall

Reports and Proceedings

RAND Corporation

Over the 20 years that same-sex couples have been able to marry in the U.S., there have been no negative effects on marriage, divorce or cohabitation among different-sex couples, according to new report from RAND and UCLA.


In addition, the few significant effects observed by new analyses of the issue suggest a slight increase in overall marriage rates and provide some evidence of improved attitudes toward marriage among young people in states after same-sex couples were granted legal status.


Researchers also reviewed nearly 100 studies that have examined the consequences of same-sex marriage on multiple measures of family formation and well-being, and found consistent results indicating significant benefits to same-sex couples and no harm to different-sex unions.


“Some of those who opposed the granting of marriage rights to same-sex couples predicted that doing so would undermine the institution of marriage, resulting in fewer couples marrying, more couples divorcing and an overall retreat from family formation,” said study coauthor Benjamin R. Karney, a UCLA psychology professor and adjunct researcher at RAND, a nonprofit research organization. “Overall, the fears of opponents of same-sex marriage simply have not come to pass.”


The study found that after states legalized marriage for same-sex couples, the number of marriages increased in those states at rates greater than what could be accounted for by the new marriages of same-sex couples alone.


“We find no evidence for a retreat from marriage,” said Melanie A. Zaber, coauthor of the report and a RAND economist. “In fact, there is evidence suggesting that by extending marriage rights to a greater number of couples, interest in marriage increased. And that finding isn’t limited to same-sex couples -- this is also true for the broader population.”


The first state-sanctioned marriage licenses for same-sex couples were issued in May 2004 in Massachusetts after its supreme court held that the state’s constitution guaranteed same-sex couples the right to marry.


Over the next 11 years, same-sex marriages were sanctioned in several other states before the U.S. Supreme Court ruled in June 2015 that state-level bans on marriage for same-sex couples violate the federal constitution, extending the right to marry to same-sex couples nationwide. Surveys now find about 70% of Americans support same-sex marriage.


Researchers from RAND and UCLA reviewed existing research that has examined how any form of legal status, including marriage and civil unions, affects the well-being of LGBT individuals, their children and the general public.


Across 96 studies reviewed by the project, researchers found that extending marriage and other forms of legal recognition to same-sex couples has been consistently positive for same-sex couples and LGBT individuals, their children and the general population.


For LGBT individuals and same-sex couples, research has found that the “marriage benefit” that has been well-documented in different-sex couples extends to same-sex couples as well. This includes lower psychological distress as compared to same-sex couples with other forms of legal status or no legal status.


The physical health of LGBT individuals in states that approved marriage between same-sex couples also improved, as demonstrated by higher levels of health insurance coverage, and declining rates of sexually transmitted infections and problematic substance use.


When states legalized marriage for same-sex couples, same-sex households in those states experienced more stable relationships, higher earnings and higher rates of home ownership.


To address limitations in earlier studies, researchers from RAND and UCLA examined multiple national data sets to study how changes in the legal status of same-sex marriages across and within states affected trends in family formation between 2000 through 2014. 

This included the causal effects of state-level policy changes on different-sex couples’ marriage rates, divorce rates and cohabitation rates.


The study found no evidence of an increase in cohabitation by unmarried different-sex couples, and some evidence of a statistically significant decline, consistent with increased interest in marriage. Similarly, researchers found no consistent evidence of an increase in divorce as a consequence of legalizing marriage for same-sex couples.


Researchers also analyzed information from an annual survey of high school seniors that asks them a series of questions about their attitudes toward marriage and family formation. While the changes in attitudes were small, researchers suggest that issuing marriage licenses to same-sex couples had, if anything, led to a small positive impact on marriage attitudes among high school seniors.


“The only changes we detect are suggestive of a renewed salience of marriage among the broader public,” Zaber said. “There is no empirical basis for concerns that allowing same-sex couples to marry has negatively affected different-sex couples and families.”


Support for the study was provided by Centerline Liberties. 


The report, “20 Years of Legal Marriage for Same-Sex Couples in the United States: Evidence Review and New Analyses,” is available at Other authors of the report are Molly G. Smith, Samuel J. Mann, Marwa AlFakhri, Jessie Coe, Jamie L. Ryan, Catria Gadwah-Meaden, Christy Mallory, Brad Sears and Chandra Garber.


The RAND Social and Economic Well-Being division seeks to actively improve the health, and social and economic well-being of populations and communities throughout the world.


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