Same-Sex Marriage Is Legal Nationwide, Supreme Court Rules In a landmark decision, the court said same-sex couples across the U.S. have the right to marry.

The Supreme Court of the United States ruled on Friday that same-sex couples have the right to marry.

The Court ruled 5-to-4, with Justices John Roberts, Antonin Scalia, Clarence Thomas and Samuel Alito dissenting. All four dissenting Justices wrote their own separate dissents.

Roberts, the Court's Chief Justice, wrote the principal dissent.

"If you are among the many Americans--of whatever sexual orientation--who favor expanding same-sex marriage, by all means celebrate today's decision. Celebrate the achievement of a desired goal. Celebrate the opportunity for a new expression of commitment to a partner. Celebrate the availability of new benefits. But do not Celebrate the Constitution. It had nothing to do with it," Roberts said.

In his dissent, Scalia said the ruling is a "threat to American democracy," adding that "Hubris is sometimes defined as o'erweening pride; and pride, we know, goeth before a fall ... With each decision of ours that takes from the People a question properly left to them—with each decision that is unabashedly not based on law, but on the 'reasoned judgment' of a bare majority of this Court—we move one step closer of our impotence."

Justice Anthony Kennedy, thought to be the swing vote on the ruling, authored the opinion.

The Supreme Court said in January it would be ruling on the matter and that it would decide two questions: Whether states must allow same-sex couples to marry and whether states must recognize same-sex marriages that take place out-of-state.

The issue had deeply divided the Court's justices and Justice Anthony Kennedy remained as the one swing vote on the matter.

According to the New York Times, Kennedy said he was concerned about changing the country's conception of marriage after so many years. However, he also said he was concerned about excluding gay families from the institution of marriage.

The ruling also has financial implications for same-sex couples.

Married opposite-sex couples enjoy plenty of Social Security benefits, such as spousal and survivor benefits, which aren't currently available to married same-sex couples in the 13 states where gay marriage is illegal. A favorable decision will mean that married same-sex couples in those states could apply for spousal and survivor benefits just like married opposite-sex couples.

Same-sex marriage is currently legal in 37 states and Washington, D.C.

—CNBC's Tom Anderson and Reuters contributed to this report.