The Science on Same-Sex Marriage

by Ronald Bailey

Wall Street Journal
April 3, 2013

Last week, the U.S. Supreme Court heard oral arguments in two cases challenging legal restrictions on same-sex marriage. Proponents and opponents sought to cudgel one another with sociological and psychological studies aiming to prove that science is on their side. Well, what does the science say?

Impact on Traditional Marriage

Some opponents told the court that same-sex marriage will undermine conventional marriage among heterosexuals. So what do the data say about how legalizing gay marriages affects conventional marriages?

A 2009 study by University of Sherbrooke economist Mircea Trandafir investigated the effect of the legalization of same-sex marriage in the Netherlands, the first country to recognize same-sex marriage. In 1998, the Dutch created registered partnerships, which are open to all couples, and in 2001 a law allowing full same-sex marriages. His analysis found that same-sex marriage leads to a decline in the different-sex marriage rate, but not in the different-sex union (marriage plus registered partnership) rate. In other words, Dutch heterosexual couples are taking advantage of the “marriage lite” registered partnership alternative.

At the time of Prof. Trandafir’s study, the chief difference between registered partnerships and marriage was that the former could be dissolved at the civil registry by mutual agreement. In a 2012 West Virginia Law Review article, Mercer School of Law professor Scott Titshaw shows that the political compromises provoked by the initial refusals to extend full marriage rights to same-sex couples result in a proliferation of civil union alternatives. Prof. Titshaw agrees with Prof. Trandafir that different-sex couples increasingly find the new marriage alternatives attractive; in effect, refusing to give full legal recognition to same-sex couples ends up diminishing the status and benefits associated with conventional marriage for everyone. Ironically, conservatives, by opposing the extension of full marriage rights to gay people, have ended up weakening the institution they sought to defend.

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