Same sex marriage is now legal in the entire US after a Supreme Court ruling striking down state marriage bans. How did we get to this point? Same-sex marriages are now legal across the entirety of the United States after a historic supreme court ruling that declared attempts by conservative states to ban them unconstitutional. In what may prove the most important civil rights case in a generation, five of the nine court justices determined that the right to marriage equality was . Gay Marriage in the United States, One Year Later. same-sex marriage was already legal in 37 states Marina Koren is a senior associate editor at The Atlantic.