(CNN) -

One voice, one message. From state and federal courts nationwide over the past year has come an astounding, near-unanimous conclusion: bans on same-sex marriage are unconstitutional.

Spurred by what the Supreme Court said peripherally one year ago on the issue, there has been rapidly evolving momentum toward a goal that seemed unimaginable barely a decade ago: a right for gays and lesbians to wed.

And it could soon be a nationwide mandate, if the justices, as expected, are asked by year's end to re-enter the political, social, and legal debate over what has been called by some the civil rights issue of the new millennium.

It is already a reality in 19 states, with Pennsylvania and Oregon in recent weeks becoming the latest to join an expanding bloc legalizing the practice. Just a decade ago, there were none.

"In theory, the justices can avoid deciding any question, particularly when there is no division, and there isn't about same-sex marriage in the lower courts -- yet," said Thomas Goldstein, an appellate attorney and publisher of SCOTUSblog.com. "But this is just too important. They can't stay out, it would be ridiculous for the nation's highest court not to decide this issue."

Can same-sex bans stand up to the Constitution?

Status in the states

Judges in more than a dozen states in the past eight months have struck down same-sex marriage bans in Utah, Idaho, Texas, Oklahoma, Arkansas, Michigan, Kentucky, Tennessee, Virginia, Oregon, Pennsylvania, Wisconsin, and New Jersey.

All cited the high court's separate ruling in the so-called "Windsor" case, which invalidated a key part of the federal Defense of Marriage Act.

Legal recognition of wedlock has long been under the discretion of individual states, but a 1996 law had defined it for federal purposes as only between one man and one woman.

That meant even legally married same-sex couples could not claim tax breaks; Social Security, pension and bankruptcy benefits; along with family medical leave protections and other provisions enjoyed by opposite-sex couples.

On constitutional due process and equal protection grounds, the divided high court on June 26, 2013, said DOMA "seeks to injure" those gay and lesbian couples afforded a marriage right in their state, since it "writes inequality into" the law.

State and federal judges have now grabbed onto the "Windsor" decision, taking the issue to its next step -- whether current same-sex marriage bans -- still in place in 31 other states -- can stand up to the Constitution.

In sweeping, often poetic language, those judges have emphatically said no.

"It is time to let that beacon of freedom shine brighter on all our brothers and sisters. We will be stronger for it," Arkansas and Pulaski County Circuit Judge Chris Piazza said in one case in May.

Appeals courts next

The next rungs on the judicial ladder are the the appeals courts, the stage of review just below the Supreme Court.

On Wednesday, a federal appeals court in Utah overturned that state's ban. Utah officials said their next stop would be Washington, although, it's unclear if the Supreme Court would take the case.

If accepted, the justices could finally answer one of the most important constitutional questions of our time: Do gays and lesbians have the same fundamental right as opposite-sex couples in all 50 states to wed?

Supporters of traditional marriage laws have a simple message: let the voters -- not the courts -- decide.

"Marriage should be a political issue that belongs to the people," said Austin Nimocks, senior counsel at the legal ministry Alliance Defending Freedom. "What should not happen is those federal judges using their judicial power to usurp the will of the people in this great debate. The last thing we need is a 50-state mandate on a question that people care about and are going to continue to debate regardless of what the courts do."

Complete discretion

The nine members of the high court have complete discretion to accept or deny any case presented to them. Their recent precedents however, give unbridled optimism to many in the gay rights and civil rights communities they will at least get their day in court. A sweeping judicial victory may be tantalizingly close.

"You never know how any Supreme Court case is going to be resolved, especially when the stakes are this high, but the challengers definitely have the upper hand," said Goldstein.

"It gives our relationship a dignity"

There are more than 140,000 same-sex couples -- or about 22 percent nationwide -- that have formalized their relationship under state law, according to UCLA's Williams Institute think tank. With the number of states legalizing it in rapid fashion in recent months, the actual numbers of legally married gay and lesbian couples remains in severe flux.

One such couple is Laurie Wood and Kody Partridge of the Salt Lake City area. They were among the first to legally tie the knot in Utah after a federal judge in late December stuck down the state's ban.

The two women have been a committed couple since 2010, but in their eyes -- having that marriage license affirms publicly what their friends, family and they themselves knew intrinsically.

"It gives our relationship a dignity, it gives it a forwardness," Wood told CNN recently. "I didn't think it would make that much difference especially, since I grew up thinking that I would never ever marry. I don't know how to explain it but it really makes a difference. People look at us differently, and for the better."

A folk hero in the LGBT community

"Legalistic argle-bargle."

That is how Justice Antonin Scalia colorfully summarized his dissent to the Supreme Court's Windsor decision a year ago.

The ruling dealt strictly with federal questions but as Scalia strongly -- and accurately -- predicted, its rationale has since been co-opted when deciding state bans on same-sex marriage. In fact, many judges have used Scalia's own words to boost their conclusions.

The justices by a 5-4 vote gave an enormous legal and political boost to those like Edith "Edie" Windsor. The 83-year-old New Yorker was forced to assume an estate tax bill much larger than heterosexual married couples would have to pay.

Because her decades-long partner was a woman, the federal government did not recognize their same-sex marriage in legal terms, even though their home state of New York did. Windsor's spouse, Thea Spyer, died several years ago. Windsor's court victory has made her a folk hero in the LGBT community.

Scalia's influence

Scalia led the opposition to the majority's decision, suggesting it would create social tension by having judges overruling voter-approved measures.

"It is one thing for a society to elect change; it is another for a court of law to impose change by adjudging those who oppose it hostes humani generis -- enemies of the human race," Scalia wrote. "In the majority's telling, this story is black-and-white: Hate your neighbor or come along with us."

Federal Judge Timothy Black cited the dissent in a December ruling, when ordering Ohio to recognize on a death certificate a legal same-sex marriage from another state. And federal Judge Robert Shelby went further, when striking down Utah's ban December 20.

Abandoning the defense