The U.S. Supreme Court’s removal of the final hurdles that littered the path to marriage equality in Idaho represents, in all likelihood, the last chapter of a story that unfolded more quickly than almost anyone could have imagined. The twists and turns of the journey to same sex marriage constitute a lesson in legal history and civic education.

In the final days of the rulings from the 9th Circuit and the U.S. Supreme Court-- judicial acts that caused emotions to soar and plummet-- Idahoans were treated to a seminar on the principles and fundamentals of the Constitution. Mindful of their constitutional and democratic right to exercise their will at the polls voters, like legislators, learned that their will is not unconstrained. While they might enact measures that reflect their views and values, they were reminded that state laws, and even state constitutional amendments, are subject to limits imposed by the U.S. Constitution, including those imposed by the Equal Protection Clause of the 14th Amendment.

Idahoans were reminded, moreover, of the importance of the Supremacy Clause and federal judicial review of state acts. The Framers of the Constitution installed the Supremacy Clause to reinforce what the entire structure of the document presupposes: the Constitution is the supreme law of the land, “notwithstanding anything to the contrary in the state constitution or state laws.” The Supremacy Clause made explicit the Constitutional Convention’s decision to remove the nation from the state-centered system of the Articles of Confederation, which exalted state sovereignty, and replace it with a new system that subordinated states to the terms and limits of the Constitution.

Enforcement of the new scheme of governance included a broad grant of authority to the federal judiciary, as supplied by Article 3 and the Judiciary Act of 1789. When state actions, including laws and constitutional amendments, were suspected of violating the Constitution, federal courts were granted the last judicial word over cases arising under federal law. All federal courts were vested with the judicial power of the United States, which meant that they could serve as courts of last resort, with no requirement that their decisions would be appealed to the U.S. Supreme Court.

It was little more than a year ago—June of 2013— that Justice Scalia rightly predicted in a passionate dissent that the Court’s decision in United States v. Windsor provided a road map for plaintiffs to overturn state bans on same sex marriage. Scalia’s prediction, more prominently quoted than any other passage in a Supreme Court opinion in recent years, is reminiscent of a more famous dissent a century before that also lamented a ruling by the High Court.

In 1896, in Plessy v. Ferguson, among the most infamous judicial decisions ever rendered, the Supreme Court held that segregation did not violate the Equal Protection Clause of the 14th Amendment. With that ruling, the court upheld Jim Crow laws, concretized apartheid in America and relegated African-Americans to second-class citizenship. In a dissent that entered the pantheon of landmark opinions, Justice John Marshall Harlan denounced his colleagues for a “pernicious” decision that created a “caste” system. “Our Constitution,” Harlan wrote, is “color-blind, and neither knows nor tolerates classes among citizens. In respect of civil rights, all citizens are equal before the law.”

Harlan’s dissent was vindicated in Brown v. Board of Education in 1954, when the Court struck down segregation in public schools. With the recent rulings on same-sex marriage from the 9th Circuit and the Supreme Court, Harlan’s vision of equality for all citizens has been vindicated once more.

David Adler is the Cecil D. Andrus Professor of Public Affairs at Boise State University, where he serves as Director of the Andrus Center for Public Policy.