In a landmark opinion, the Supreme Court ruled Friday that states cannot ban same-sex marriage, handing gay rights advocates their biggest victory yet.The 5-4 ruling had Justice Anthony Kennedy writing for the majority with the four liberal justices. Each of the four conservative justices wrote their own dissent.The far-reaching decision settles one of the major civil rights fights of this era -- one that has rapidly evolved in the minds of the American pubic and its leaders, including President Barack Obama. He struggled publicly with the issue and ultimately embraced same-sex marriage in the months before his 2012 re-election."No union is more profound than marriage, for it embodies the highest ideals of love, fidelity, devotion, sacrifice and family," Kennedy wrote. "In forming a marital union, two people become something greater than they once were."In a dissent, Justice Antonin Scalia blasted the Court's "threat to American democracy.""The substance of today's decree is not of immense personal importance to me," he wrote. "But what really astounds is the hubris reflected in today's judicial Putsch."