The Supreme Court’s decision legalizing same-sex marriage across the nation is in the news again with the House’s passage last week of legislation codifying that 2015 ruling as part of U.S. law.

In the years before the high court ruled in the case known as Obergefell v. Hodges38 states defined marriage by law as an exclusive union between one man and one woman. 

In 31 of these states, voters approved ballot initiatives to amend their state constitutions to define marriage that way. (See the full list below or in the chart here.)

A total of 35 states still have these laws—whether in the state constitution, statute, or both—on the books.  

In most states, according to Heritage Foundation research, an overwhelming percentage of voters favored a state constitutional amendment defining marriage as the union of one man and one woman. 

In Mississippi, 86% of voters in 2004 supported that traditional definition of marriage, as did 81% in of Alabama in 2006. That same year, 81% of voters in Tennessee, 78% in South Carolina, and 63% in Idaho favored such an amendment. 

Even in California, as late as 2008, a slight majority (52%) voted to protect the traditional definition of marriage.

By late 2013, however, at least 16 states and the District of Columbia had redefined marriage to include same-sex unions.

Massachusetts forged the way, legalizing same-sex marriage in 2003 following a decision by its Supreme Judicial Court. 

Same-sex marriage was legalized through judicial rulings in several other states as well. The supreme courts of Connecticut and of Iowa did so in 2008 and 2009, respectively. State courts in New Jersey and New Mexico legalized same-sex marriage in 2013. 

That June, the U.S. Supreme Court allowed lower courts in California to overturn Proposition 8’s definition of marriage as decided by voters. At that point, same-sex marriage again became legal in the Golden State. 

Other states—and the District of Columbia—redefined marriage through legislation. According to Pew Research, New Hampshire, Vermont, and the District all did this in 2009. 

Hawaii, Delaware, Illinois, Minnesota, and Rhode Island passed legislation in 2013 that broadened the legal definition of marriage to include same-sex unions. 

Maryland, Maine, and Washington legalized same-sex marriage by popular vote, all of them in 2012. Heritage Foundation research shows that voters approved these measures by relatively small margins, however: 52% in Maryland, 53% in Maine, and 54% in Washington state. 

“The Obergefell case is a textbook example of what happens when an issue falls out of politics,” Terry Schilling, president of the American Principles Project, told The Daily Signal in a remark on the 2015 Supreme Court ruling. “At the time the decision was handed down, support for same-sex marriage had been inching up, but the ultimate outcome of the debate was still unclear, as voters in many states continued to oppose it.”

Utah, Oklahoma, Virginia, Indiana, and Wisconsin were among the states that originally defined marriage as one man and one woman. In 2014, however, the Supreme Court declined to hear these states’ petitions on the definition of marriage. As a result, lower court decisions that revoked existing marriage laws took effect in each of the five states. 

In one of these rulings, Judge Richard Posner of the 7th U.S. Circuit Court of Appeals stated in his majority opinion: “The governments of Indiana and Wisconsin have given [the court] no reason to think they have a ‘reasonable basis’ for forbidding same-sex marriage.”

Ryan T. Anderson, a former senior fellow at The Heritage Foundation, argued that this Supreme Court ruling was “an unfortunate setback for sound constitutional self-government and a setback for a healthy marriage culture.” 

As Anderson put it at the time, laws defining marriage as between a man and a woman in those five states, and others, were “frequently passed with overwhelming democratic support.” 

Supreme Court Justice Samuel Alito is among conservatives who have said no effort is underway to overturn Obergefell, as Democrats claim. Indeed, public opinion on marriage has changed since the high court’s Obergefell ruling in 2015. 

As Schilling said: “The political movement to defend traditional marriage has gone nearly invisible post-Obergefell. As a result, it should be no surprise that opposition to same-sex marriage in public opinion has largely collapsed.”

According to one Gallup poll, 70% of Americans supported same-sex marriage in 2021—an increase of 10 percentage points in the six years since Obergefell. 

The 31 states where voters decided before the Obergefell ruling that marriage is between one man and one woman are, alphabetically: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Idaho, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Montana, Nebraska, Nevada, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, and Wisconsin.

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