Legal experts, supporters and opponents of same-sex marriage seem to agree: Taken together, the U.S. Supreme Court's two decisions on Wednesday concerning same-sex marriage are hugely important.

Calling it "the Cinderella moment for the lesbian and gay marriage equality movement," Yale law school professor William Eskridge told CBC News that "as a legal and constitutional matter, the traditional presumption against state recognition of all lesbian, gay, bisexual and transgendered

[LGBT] couples has been reversed and the momentum is now on the side of marriage equality."

Stuart Gaffney of Marriage Equality USA, speaking to CBC News by telephone from a huge celebration outside San Francisco's city hall immediately following the court decisions, said "we are ecstatic to get another landmark ruling from the Supreme Court … advancing the rights of LGBT Americans towards full citizenship."

Edith Windsor, the woman at the heart of one those decisions, said that "because of today's Supreme Court ruling, every child born today will be able to grow up in a world … where the federal government won't discriminate against their marriages no matter who they are."

And Rev. Albert Mohler, the president of Southern Baptist Theological Seminary, says on his website of the rulings that "both will go far in redefining the most basic institution of human civilization," adding that "future generations will indeed remember this day."

How the court ruled

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Supreme Court Justice Anthony Kennedy wrote the Supreme Court's majority opinion that the Defence of Marriage Act is unconstitutional because it 'violates basic due process and equal protection principles.' (Rich Pedroncelli/Associated Press)

In the first decision, the Supreme Court ruled that the 1996 Defence of Marriage Act [DOMA] is unconstitutional because it "violates basic due process and equal protection principles applicable to the federal government," as Justice Anthony Kennedy puts it in the majority opinion.

In language considered very strong and sweeping, Kennedy stated that "DOMA’s avowed purpose and practical effect are to impose a disadvantage, a separate status, and so a stigma upon all who enter into same-sex marriages made lawful by the unquestioned authority of the states."

Even Justice Antonin Scalia, writing for the minority, called the court's decision "jaw-dropping."

He complains that, "By formally declaring anyone opposed to same-sex marriage an enemy of human decency, the majority arms well every challenger to a state law restricting marriage to its traditional definition."

Windsor, 83, who got married in Toronto in 2007, started the case after the U.S. government required her to pay an estate tax of $363,000 because it did not recognize her same-sex marriage. Windsor should now get her money back.

Gay marriage legal again in California

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Rev. Albert Mohler, president of the Southern Baptist Theological Seminary, expects a decision from the Supreme Court in the near future that will rule on 'coast-to-coast legalization of same-sex marriage.' (SBTS/Associated Press)

The second case concerns California's Proposition 8, which was approved in a 2008 referendum and bans same-sex marriage in the state. A lower court later ruled against the proposition.

The Supreme Court decided it has "no authority to decide this case on the merits" because the proponents of Proposition 8 that argued the case before it did not have legal standing.

Normally the government of California would be the ones appealing a ruling that strikes down a California law, but in this case it did not do so because it does not support Proposition 8.

The result of this Supreme Court decision is that same-sex couples will once again be allowed to get married in California.

Comparing the U.S. and Canadian supreme courts

If the Supreme Court of Canada were to face a case similar to the Proposition 8 decision in which the U.S. Supreme Court just ruled, the Canadian justices would likely "appoint a 'friend of the court' to represent any side they thought wasn't fairly represented," University of Ottawa law professor Carissima Mathen told CBC News.

While the U.S. decisions do not determine whether or not same-sex marriages are legal in the U.S., when  the Supreme Court of Canada made its famous same-sex marriage ruling it also did not provide an answer.

The question was put to the court whether, under the Charter of Rights and Freedoms, it's a violation of equality to have an opposite-sex-only definition of marriage. Mathen says, "The court ruled it would be inappropriate for it to answer that question."

"It's now a moot point because of the Civil Marriage Act passed by Parliament" in 2005, she added.

Eskridge says that when it comes to recognizing marriage equality, "Canada will always get credit as the pioneer country in North America."

Eskridge said the reasoning behind that decision is that, "Harms of a purely political or ideological nature that are not a particular legal harm to you will not allow you to come into federal court to sue or to take an appeal."

Eskridge is one of the leading experts in this area of U.S. law. He was also an expert witness in the Ontario case that led to the Supreme Court of Canada's landmark decision in 1999 on the rights of same-sex couples.

He says the Prop 8 ruling will probably not have a direct impact outside California, but he expects it will make it more likely that now there will be "more public officials refusing to defend indefensible discrimination."

Before the court's decision, the expectation from all sides was that the ruling on Proposition 8 would be the most important, but now there's agreement that, in Mohler's words, "the DOMA decision is, by far, the most important and wide reaching."

What's next?

Mohler, while critical of the Supreme Court ruling, says "it sets up a future legal challenge from any citizen in any state that does not have legal same-sex marriage.

"The court’s decision in that future case, surely not long in our future, will be the new Roe v. Wade — a sweeping decision that would create a new 'right' that would mean the coast-to-coast legalization of same-sex marriage."

For now, the decisions do not mean a state has to allow same-sex marriage.

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William Eskridge of Yale University told CBC News it's now up to the Obama administration to work out what happens in states that don't recognize same-sex marriages when a married same-sex couple moves to or lives in that state. (Courtesy Yale Law School)

Eskridge says they do mean it's now up to the Obama administration to work out what happens in states that don't recognize same-sex marriages when a married same-sex couple moves to or lives in that state. The Supreme Court did not provide an answer on Wednesday.

John Lewis, Gaffney's husband and the Marriage Equality USA's legal director, was also at the celebration in San Francisco. Amid the bedlam around him, he told CBC News to expect "to see a movement to achieve marriage equality through the legislatures." With the momentum his side of the debate now has, he expects many more states "will become in favour of the freedom to marry."

Gaffney added that "we have a lot of wedding planning to do before we fan out through the country to make full equality the reality."