A supporter of same-sex marriage wears a rainbow flag in front of the Supreme Court in 2013. (Andrew Harrer/Bloomberg)

My initial excitement Friday about the Supreme Court finally agreeing to consider whether the Constitution holds a right to same-sex marriage was almost immediately replaced with panic. The trigger was the first of two questions the court will consider: “Does the Fourteenth Amendment require a state to license a marriage between two people of the same sex?”

“State” was what set off alarms for me. States have the power to regulate who can and cannot marry. That’s one of the reasons why the so-called Defense of Marriage Act (DOMA) was so odious. Aside from being discriminatory, the federal legislation trampled on a state’s right to determine whether a same-sex couple could marry. Now the court is asking whether the Constitution requires a state to do so. A quick e-mail and phone call to Evan Wolfson, the founder and president of Freedom to Marry, put me at ease.

“The bottom line answer to your question is that while states regulate marriage, they do so under the Constitution. There is a floor below which the states may not go, and that floor is the Constitution’s guarantee of the freedom to marry and equal protection under the law,” Wolfson wrote in response to my e-mail. “Loving v. Virginia and other important freedom to marry cases have affirmed both of those guarantees, the very guarantees nearly 60 state and federal courts have invoked in the waves of rulings in favor of the exclusion of gay couples from marriage.”

The Loving ruling is vitally important to the expected outcome of the justices’ impending deliberations for three reasons: the Constitution, the states and the American people. For Wolfson, these three reasons have served as the benchmark for ultimate victory for marriage equality.

The Supreme Court ruled in that 1967 case that Virginia’s ban on marriages between people of different races violated the equal protection guarantee of the 14th Amendment of the Constitution. “The freedom to marry has long been recognized as one of the vital personal rights essential to the orderly pursuit of happiness by free men,” the majority argued. “To deny this fundamental freedom on so unsupportable a basis as the racial classifications embodied in these statutes, classifications so directly subversive of the principle of equality at the heart of the Fourteenth Amendment, is surely to deprive all the State’s citizens of liberty without due process of law.” Replace “racial classifications” with “sexual orientation” and the argument rationale still holds.

By the time the Loving case was decided, Virginia was one of 16 states that still outlawed interracial marriage. As for public opinion, well, the American people were overwhelmingly against such unions. A Gallup poll in 1968, a year after the Supreme Court ruling, showed 73 percent disapproval. When the justices hear arguments in late April, the conditions will be more favorable for same-sex marriage.

Interracial marriage was legal in 34 states by the time Loving was decided. Marriage equality is now legal in 36 states and the District of Columbia. According to the Williams Institute, “[M]ore than seven-in-ten (70.4%) Americans are living in states that allow marriage for same-sex couples.” And support for same-sex marriage is above 50 percent. The Gallup poll puts it at 55 percent. The Post-ABC News poll shows 59 percent approval.

One more thing. There have been 59 favorable rulings for marriage equality since the Supreme Court’s historic rulings in 2013. Wolfson told me that his favorite line from one of those rulings came from Judge Robert Shelby. “It is not the Constitution that has changed,” the federal jurist who struck down Utah’s ban on same-sex marriage in Dec. 2013, “but the knowledge of what it means to be gay or lesbian.”

“Just being right is not enough,” Wolfson told me with the confidence that has bolstered him for more than 30 years. “We have the support. We have the states and we’re right.” After hearing him say that, I had to agree with Buzzfeed’s Chris Geidner, who wrote just as confidently over the weekend about the coming Supreme Court decision, “[T]he outcome is almost certain.”

Follow Jonathan on Twitter: @Capehartj