Which 2013 supreme court decision ruled that the defense of marriage act violated the equal protection and was unconstitutional?

United States v. Windsor is considered a landmark decision. The civil rights case decided that restricting marriage or the title of a spouse to only the opposite sex was unconstitutional under the Due Process Clause. The plaintiffs were married in Canada, which was legal in 2013, and lived in New York.

The 2013 Supreme Court Decision was 'United States vs. Windsor', this was a federal civil rights case in the matter that the government restricted the understanding of marriage only to the opposing gender. 

B- protecting freed african americans