June 26, 2013  -- The Supreme Court handed down two rulings today bolstering same-sex marriage by ruling part of the Defense of Marriage Act unconstitutional and allowing a lower court ruling to stand that struck down California's Proposition 8 ballot initiative, which defines marriage as between one man and one woman.

In the first decision, the court ruled today that a portion of the Defense of Marriage Act (DOMA), which denies federal benefits to same-sex couples, is unconstitutional.

And in a separate opinion, the court dismissed a case that asked the court to overturn a lower-court decision striking down the California marriage law. The decision paves the way for marriages to resume in California.

"Thanks to these historic decisions today, we are one step closer to finally realizing those words inscribed on that building behind me 'Equal justice under the law,'" said Chad Griffin, president of the gay rights advocacy group the Human Rights Campaign, outside the Supreme Court. "Today at long last this nation has wiped away the shame of Proposition 8 and the discriminatory Defense of Marriage Act once and for all."

But lawyers for the plaintiffs defending Proposition 8 said that they will continue to defend the initiative.

"We're disappointed about the Supreme Court's decision on standing, but we are happy that proposition 8 does remain the law in the state of California," said Austin Nimocks, senior counsel with Alliance Defending Freedom which argued for the plaintiffs in defense of Proposition, outside of the Supreme Court today. "The proponents of Proposition 8 and the legal team defending it will continue to defend proposition 8 unless and until there is an appellate court decision from a court with jurisdiction that strikes it down."

Defenders of the initiative say they will seek a "binding and enforceable" state-wide order preventing Proposition 8 from being enforced by California laws, a move that could set off a protracted legal battle going forward.

READ MORE: Same-sex couples cheer DOMA's demise.

Reactions from Democratic lawmakers poured in shortly after the court ruled.

President Obama, who is traveling to Africa on Air Force One today called the plaintiffs in the Defense of Marriage Act case, congratulating them on their victory.

In a statement, the president said that he applauds the court's decision to strike down "discrimination enshrined in law."

"The Supreme Court has righted that wrong, and our country is better off for it. We are a people who declared that we are all created equal – and the love we commit to one another must be equal as well," Obama said. "This ruling is a victory for couples who have long fought for equal treatment under the law; for children whose parents' marriages will now be recognized, rightly, as legitimate; for families that, at long last, will get the respect and protection they deserve; and for friends and supporters who have wanted nothing more than to see their loved ones treated fairly and have worked hard to persuade their nation to change for the better."

On behalf of Republican lawmakers in the House, who defended DOMA in the courts, Speaker John Boehner expressed disappointment that the court ruled against the 1996 law.

"The House intervened in this case because the constitutionality of a law should be judged by the Court, not by the president unilaterally," Boehner said in a statement. "While I am obviously disappointed in the ruling, it is always critical that we protect our system of checks and balances."

"A robust national debate over marriage will continue in the public square, and it is my hope that states will define marriage as the union between one man and one woman," he added.

READ MORE: How the Supreme Court Decided on DOMA.

Justice Anthony Kennedy wrote the opinion for the court striking down section 3 of DOMA in a 5-4 decision.

"DOMA violates basic due process and equal protection principles applicable to the federal government," Kennedy said. "Under DOMA same-sex married couples have their lives burdened, by reason of government decree, in visible and public ways."

"By its great reach DOMA touches many aspects of married life from the mundane to the profound," he added.

On Proposition 8, the court avoided making a sweeping decision on the constitutionality of gay marriage restrictions, but dismissed the case by saying that the parties defending Proposition 8 did not have the right to appeal the lower court's ruling.

The case concerned a challenge to the controversial California ballot initiative passed in 2008 that defines marriage as between one man and one woman.

Because California officials declined to defend the law in Court, lawyers for the original sponsors of the initiative--a group called Protectmarriage.com--stepped in to do so. Lawyer Charles J. Cooper argued that Californians who voted in favor of Prop 8 opted "in good faith" to preserve the traditional definition of marriage because they believe it continues to meaningfully serve important societal interests.

READ MORE: Proposition 8: Supreme Court Ruling Explained.

Chief Justice John Roberts read the court's opinion dismissing the Proposition 8 case on the basis that the "petitioners did not have standing to appeal the District Court's order."

The DOMA case was brought by Edie Windsor, an 83-year-old woman from New York who married Thea Clara Spyer in 2007 after some 40 years together as a couple. When Spyer died in 2009, Windsor was denied, under DOMA, an exemption on federal estate taxes on her spouse's estate.

The court's ruling prohibits the federal government from denying benefits to same-sex couples who are legally married in the 12 states that currently recognize same-sex marriages.

The case involved a challenge to the 1996 law that passed with wide majorities and that defines marriage as between a man and a woman. It denies federal benefits to same-sex couples who are legally married in their states.

"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," Kennedy wrote in an opinion that was joined by Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan.

Crowds outside the Supreme Court could be heard erupting in applause as news of the court's ruling spread.

Justice Antonin Scalia, who dissented along with conservative Justices John Roberts, Clarence Thomas, and Samuel Alito, read his dissent from the bench.

He said that he doesn't believe the court had the jurisdiction to hear the case.

"There are two parts to the majority's opinion, the first explaining why this Court has jurisdiction to decide the question, and the second deciding it," Scalia said. "Both of them are wrong, and the error in both springs from the same diseased root: an exalted notion of the role of this Court in American democratic society." Read ABC News' live blog of the Supreme Court's decisions HERE.