Photo credit to Joe Henchman.

With today’s breathtaking victory for marriage equality in the case of Obergefell v. Hodges, the U.S. supreme court, the United States of America joins the ranks of less than two dozen countries across five continents that recognize full equality as between opposite-sex and same-sex marriages.

Generally speaking, there are three ways that countries have gone about enacting same-sex marriage. The first and, by far, the most popular route is through direct legislation, as the United Kingdom, France and many other countries have done. The second is through popular referendum — Maryland and Washington took this path within the United States in 2012 and Ireland, most recently, did so in a near-landslide victory on May 22. The third route is when constitutional courts find that the refusal to provide state-sponsored marriage benefits to a same-sex couple violates a country’s fundamental governing charter.

In that regard, the US path to universal marriage equality is unique. South Africa’s constitutional court in 2005 essentially forced the country’s parliament to enact legislation in 2006, and Brazil’s constitutional court ruled in favor of marriage equality in 2013.

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RELATED: After Irish vote, what next for same-sex marriage in Europe?

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The problem with the legislative path — and especially with the referendum path — is that they both set the precedent in world politics that it’s perfectly fine to leave the rights of a minority group up to the whims of everyday politics. Marriage equality supporters may love that Irish voters delivered such a strong verdict for same-sex marriage, but it subtly validates votes in places like Croatia in 2013, where voters rejected marriage equality by vote. If, in 2019, Poland decides to hold a referendum and Polish voters reject same-sex marriage, the 2015 Irish referendum will nevertheless validate the direct democracy approach — namely, that a popular vote should be able to establish or deny fundamental rights.

Instead, here’s a sampling of what Anthony Kennedy wrote in his ruling today:

Laws excluding same-sex couples from the marriage right impose stigma and injury of the kind prohibited by our basic charter….

These considerations lead to the conclusion that the right to marry is a fundamental right inherent in the liberty of the person, and under the Due Process and Equal Protection Clauses of the Fourteenth Amendment couples of the same-sex may not be deprived of that right and that liberty.

Not only does the ruling mean that the United States is now more progressive on LGBT rights than much of Europe and the rest of the Western world, it also sets a precedent with which constitutional courts worldwide will now have to grapple.

The decision stands for the idea, long applied to protection on the basis of race, ethnicity and gender, that there are certain principles in a liberal democracy that are ‘above’ petty political fights. Legal scholars will recognize this idea as a principle that flows back to famous footnote in a 1938 ruling, United States v. Carolene Products Company:

There may be narrower scope for operation of the presumption of constitutionality when legislation appears on its face to be within a specific prohibition of the Constitution, such as those of the first ten amendments, which are deemed equally specific when held to be embraced within the Fourteenth. . . . whether prejudice against discrete and insular minorities may be a special condition, which tends seriously to curtail the operation of those political processes ordinarily to be relied upon to protect minorities, and which may call for a correspondingly more searching judicial inquiry…

The bottom line is that constitutional courts — for example, those in Australia and Israel, Germany and Italy, or even the European Court of Human Rights, will feel significantly greater pressure as a result of today’s holding in Washington, D.C. Germany’s constitutional court, the Bundesverfassungsgericht, for example, has been nudging the country ever so closely to marriage equality in a series of rulings that have almost eliminated the difference between ‘life partnerships’ and marriage.