The U.S. Supreme Court struck down the Federal Defense of Marriage Act which defines marriages as the union of a man and a woman Wednesday.
Writing for the majority, Justice Anthony Kennedy said DOMA violates gays' equal protection rights under the law.
In a separate decision, the court said the defenders of California's proposition eight had no standing to bring the case before the court.
That means a lower court ruling will stand and same sex couples will soon be able to get married in California.
Reactions have been mixed:
"Marriage—that is something that God created. That is something that God will define. The Supreme Court -- though they may think so -- have not arisen to the level of God," said Representative Michele Bachmann from Minnesota.
"Huge...I'm so overwhelmed, I'm so excited. I honestly...have told everybody I was expecting this, but it's still a shock. I'm so excited," said Jean Podrasky, the Cousin of Chief Justice John Roberts.
Wednesday's rulings do not have a broad impact on the country as a whole, only those states that have legalized same-sex marriage are affected.
The 35 states where those unions are illegal will see no change—that includes South Dakota.
This Supreme Court ruling is certainly a historic step for the Gay Rights movement, but looking at Supreme Court cases throughout U.S. history, Wednesday's decision could be just the first of many rulings to come.
"There could be a lot more litigation coming up which makes this a really exciting area of constitutional law because if other states deny same sex marriage, are they violating the equal protection clause," said Julie Lane, Assistant Professor of Political Science at SDSU.
It's a question that has eventually landed in front of the Supreme Court throughout many discrimination cases in history.
"Over time the U.S. Supreme Court has applied the equal protection of the law provision to more and more different forms of discrimination," said political analyst Bob Burns.
With the Civil Rights movement, it took several rounds of federal decisions involving the equal protection clause in the 14th amendment before some landmark cases like Loving v. Virginia came about, requiring all states to recognize interracial marriages.
Many believe this type of federal requirement is the next stop for same-sex marriage legislation.
"With the momentum that's going now with more and more states passing these laws, there will be a lot more happening," said Lane.
But historically, even after an all inclusive Supreme Court ruling, it can take states quite a while to implement the required changes.
"The desegregation was to proceed with all deliberate speed—well 10 years later, many of the states had stubbornly resisted with all kinds of shenanigans and trickery and avoided integration," said Burns.
Should the Supreme Court require states to recognize same sex marriage, many believe a similar resistance would follow in some states, including South Dakota.
"It's a very conservative state so it could be quite some time and I think they will resist," said Lane.
If same sex marriage does become a state requirement in the future, it will very likely not be the end of the road for the gay rights movement. Looking at the journey the women's rights movement in Supreme Court cases, there have been hundreds of rulings years after the Supreme Court made a landmark ruling for women's rights in the 1970s.