Not surprisingly, the U.S. Supreme Court's landmark 5-4 ruling that the Constitution guarantees a right to same-sex marriage has generated a lot of reaction. What is surprising, however, is that, as far as I can tell, no one has commented on how prominent a role the Declaration of Independence played in Justice Clarence Thomas's dissenting opinion in the case. Never before has a Supreme Court justice cited the Declaration so frequently, and it is important to understand the reason Thomas did so, especially as the nation celebrates the anniversary of our founding document on the Fourth of July.

Justice Thomas opened and closed his opinion by invoking the Declaration, and the bulk of his dissent was devoted to explaining why: Because, in his judgment, "Our Constitution — like the Declaration of Independence before it — was predicated on a simple truth: One's liberty, not to mention one's dignity, was something to be shielded from — not provided by — the State. Today's decision casts that truth aside."

Thomas's commitment to the Declaration of Independence traces to his days as chairman of the U.S. Equal Employment Opportunity Commission during the Reagan Administration. There, he immersed himself in literature about the nation's founding document to try to find solutions to the problem of discrimination in America. His critics strived during his Supreme Court confirmation process to mischaracterize his views about it.

Harvard Law School Professor Laurence Tribe, for example, wrote in a scathing New York Times op-ed that Thomas would use the Declaration to turn back the clock to the darkest days of the nation's history: "Most conservatives criticize the judiciary for expanding its powers, 'creating' rights rather than 'interpreting' the Constitution. … Clarence Thomas, judging from his speeches and scholarly writings, seems instead to believe judges should enforce the Founders' natural law philosophy — the inalienable rights 'given man by his Creator' — which he maintains is revealed most completely in the Declaration of Independence."

What critics such as Tribe failed to mention was that Thomas was articulating the standard Anglo-American conception of liberty in his speeches and writings about the Declaration. Indeed, Thomas made this point repeatedly during his confirmation battle. For instance, when asked by then-Senator Howard Metzenbaum, D-Ohio, about a speech he had previously given,

Thomas responded: "[T]he point I think throughout these speeches is a notion that we should be careful about the relationship between the government and the individual and should be careful that the government itself does not at some point displace or infringe on the rights of the individual. That is a concern, as I have noted here, that runs throughout my speeches."

Justice Thomas's gay marriage dissent is a tour de force on the relationship between the individual and the government, especially in its discussion of the writings of John Locke, the 17th century English philosopher whose ideas about government influenced America's founders more than any other. As Thomas himself put it, "The founding-era understanding of liberty was heavily influenced by John Locke, whose writings 'on natural rights and on the social and governmental contract' were cited '[i]n pamphlet after pamphlet' by American writers."

Perhaps most important of all, Justice Thomas's commitment to the Declaration of Independence has an impressive pedigree: Thomas Jefferson, the Declaration's author, characterized our founding document as "an expression of the American mind;" Abraham Lincoln, America's only true poet/president, described the Declaration as an "apple of gold" and the Constitution as the "frame of silver" around it; and Martin Luther King Jr. constructed the most famous speech of the 20th century, "I Have a Dream," around the promise of equality to which the Declaration dedicated the nation.

In short, what Jefferson meant to the Declaration of Independence in the 18th century, and what Lincoln and King meant to it in the 19th and 20th centuries, Clarence Thomas means to it today. And while Justice Thomas's was a dissenting opinion in the gay marriage case, I couldn't help but notice that Justice Antonin Scalia — long a critic of Thomas's attempts to weave the principles of the Declaration into the fabric of American law — not only joined Thomas's dissent in its entirety but also invoked the Declaration in a separate dissenting opinion of his own.

English writer G. K. Chesterton famously remarked that "America is the only nation in the world that is founded on a creed. That creed is set forth with dogmatic and even theological lucidity in the Declaration of Independence; perhaps the only piece of practical politics that is also theoretical politics and also great literature." Whatever one thinks of the Supreme Court's recent gay marriage decision, Justice Thomas's dissenting opinion in the case needs to be understood for what it is: The most significant public pronouncement about the Declaration of the 21st century.

Scott Douglas Gerber is a law professor at Ohio Northern University. His eight books include "First Principles: The Jurisprudence of Clarence Thomas." Thinking of submitting an op-ed to the Washington Examiner? Be sure to read our guidelines on submissions.