Originalism was supposed to simplify things. Instead of vague and ever-shifting balancing tests based on judges’ impressions of what was good for society, originalism was a return to asking that basic question: What did the words mean to people at the time they were enacted? Don’t like the result? Change the law, don’t pretend it “evolved” through self-interested interpretation.

The Original Meaning of the Fourteenth Amendment: Its Letter and Spirit ; Randy E. Barnett and Evan D. Bernick ; Harvard University Press ; 488 pp., $35

This also has the virtue of being true — things are what they are, laws say what they say, and we harm the idea of law itself when we pretend otherwise. Once a niche academic position, originalism has become the dominant method of legal interpretation, first on the Right, but increasingly on the Left as well.

But there are always complications. What happens when words and phrases have uncertain meanings, or when laws were passed in a time of great change amid wide-ranging debate about the basic nature of American rights and freedoms? In The Original Meaning of the Fourteenth Amendment: Its Letter and Spirit, authors Randy Barnett and Evan Bernick dive into this question, giving us the most detailed legal history to date of the constitutional amendment that changed American law more than any before or since.

The effort was sorely needed. While scholars have pored over every known utterance associated with the 1787 Constitutional Convention, the debates around the Reconstruction amendments (the 13th, 14th, and 15th) have not attracted the same level of historical scrutiny.

Perhaps this is owing to the history of 14th Amendment case law, a patchwork of “living constitution” confusion created by earlier versions of the Supreme Court that were far less concerned with history and original understanding. Maybe it has even earlier roots, dating back to the first 14th Amendment decisions, including the evocatively named Slaughter-House Cases, in which an even earlier court dramatically limited the impact of the far-reaching amendment. In the face of a mountain of bad precedent, the effort to unearth the original public understanding of the 14th Amendment might have felt like a waste of effort.

Barnett, director of the Georgetown University Center for the Constitution, and Bernick, assistant professor of law at Northern Illinois University, disagreed, and the corpus of legal scholarship is richer for it. Their deep investigation into what was meant by phrases such as “privileges or immunities,” “due process of law,” and “equal protection of the laws” reveals a long history (especially for the first two phrases) but not always a clear contemporary consensus on their meanings.

It is striking how much of the effort around the 14th Amendment centered on the Old Northwest, the part of the United States north of the Ohio River and east of the Mississippi. The amendment’s primary author was John Bingham, a congressman from Ohio, and in the Senate, its primary advocate was Jacob Howard of Michigan. Even beyond those men, whose words shaped contemporary opinion on the 14th, the leading lights of the movement for a new national, equal citizenship also came from that region. Their ideas were influenced by New Englanders such as William Lloyd Garrison and Lysander Spooner, just as much of that region was settled by people from New England, but in the Northwest, ideas of freedom that had developed in the Revolution were brought into their full flower.

Free of the weight of the Old World that overshadowed the Eastern Seaboard and thrust into a rapidly developing former wilderness, settlers of the Northwest Territory had the space to invent a new idea of national citizenship. Outside of the class structure of the east, they had the chance to develop a land based in equal opportunity. And, crucially, because of the foresight of the Confederation Congress, they did it all in a land that was never touched by the taint of slavery.

From such beginnings arose the ideas that would, by the Reconstruction era, come to embody a new idea of American citizenship. Congress sought to apply that vision to the whole nation, including the former slaves in the South, through the Civil Rights Act of 1866, written by Bingham and Sen. Lyman Trumbull of Illinois. When President Andrew Johnson shocked the Legislature by vetoing that bill, Congress overrode him. They also came to understand that ideas as important as these must be made safe for all time by writing them directly into the Constitution.

Of the five sections of what became the 14th Amendment, three are rarely invoked, and another is halfway dormant. But Section 1, in just a few words, encapsulates the 40th Congress’s vision of what the postwar America would be:

“All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.”

Barnett and Bernick dive into these phrases and guide the reader through all the possible explanations of what they might have meant to people in 1868.

For “privileges and immunities,” there is a long history dating back to the laws of England, which makes the phrase a term of art familiar to the framers of the amendment — not least because it appears in Article 4 of the Constitution in nearly identical language. That it is not precisely identical is important here, and debates over the interpretation of that existing clause informed what Bingham, Howard, and others thought of the new version.

The authors spend most of the book interpreting these words, which makes sense: They were, from the beginning, meant to do the main work of the amendment and the postwar settlement. In Barnett and Bernick’s words, “the Privileges or Immunities Clause protects civil rights that are deemed fundamental to Republican citizenship.”

The courts saw it differently, and since the Slaughter-House Cases were decided in 1873, the clause has meant far less. The Supreme Court held that interpreting it to mean that fundamental rights now had national protection “radically changes the whole theory of the relations of the State and Federal governments to each other.” Finding this either implausible or unpalatable, they instead drastically narrowed the effect to merely protect rights that were exclusively federal, such as running for federal office or using the navigable waters of the U.S.

Nearly all modern legal scholars dispute that holding. Barnett and Bernick suggest, with ample evidence, that the original understanding of the privileges or immunities clause was far greater, “an effort to reconstruct American citizenship” as something containing a federal guarantee of all fundamental rights, enumerated and unenumerated, without regard to race or other factors. It was the radical equality of the Old Northwest frontier applied to the nation at large.

Legal history took a different course, though, and what accomplishments can be credited to the 14th Amendment have been forced through the back door of the due process clause. The results have been mostly the same, though not completely and with considerable delay. For this reason, no less an originalist than Justice Antonin Scalia rejected attempts to return to the original interpretation of the amendment, calling the campaign “the darling of the professoriate” and suggesting that the existing law, muddled as it is, does the job well enough to justify leaving it in place.

Justice Clarence Thomas famously disagrees, and some of the younger justices have shown signs of joining the effort. For Barnett and Bernick, two members of that professoriate, to insist on the effort might seem as quixotic as Scalia said, even if the results are mostly the same. They argue that having a court rely on a misbegotten theory in so many important cases diminishes its legitimacy — a problem in an age when all branches of government hold less and less respect from the people.

But beyond utility, the authors simply believe it is true. If originalism is to mean anything, it must mean following the truth about a law, wherever it may lead. If the historical evidence lends itself to Barnett and Bernick’s interpretation being true (and this is still a matter of lively debate), then that is reason enough for courts to rule that way.

The framers of the Reconstruction amendments had a broad vision, and Congress and the states gave that vision the force of law. The original public understanding of that vision, be it liberal or conservative by modern definitions, is what courts should impose. Figuring out what that is, exactly, is the hard part. But in knowing what to do with the answer, originalism makes the rest easy.

Kyle Sammin is the senior editor of the Philadelphia Weekly and the co-host of the Conservative Minds podcast. Follow him on Twitter at @KyleSammin.