Ganesh Sitaraman contends that the U.S. political system is “increasingly rigged to work for economic elites.” (Aaron Josefczyk/Reuters)

James Gray Pope is a professor of law at Rutgers University.

Ganesh Sitaraman wrote his new book, “The Crisis of the Middle-Class Constitution,” before voters went to the polls in November. But he saw enough in the Donald Trump and Bernie Sanders primary campaigns to assess the significance of the election. “After thirty years of a collapsing middle class,” he writes, “after thirty years of an economy designed to stack the deck in favor of the big guys; after thirty years of a political and constitutional system increasingly rigged to work for economic elites — after all this, the people revolted.”

To Sitaraman, this people’s revolt sounds a clarion call to all Americans: Do something about economic inequality, or face nothing less than the decline and fall of the American republic. In a wonderfully concise and well-documented chapter, “How Economic Inequality Threatens the Republic,” he explains the dynamics of rising inequality and its impact on the political system. Many of the raw facts are familiar — for example, that the 20 wealthiest Americans own more than the bottom half of the population, or 152 million people. So are many of the mechanisms by which wealth is parlayed into political power: campaign contributions, lobbying and the proverbial revolving door. But Sitaraman goes deeper to show how inequality is dividing Americans on the level of psychology and culture. Surrounded by the evidence of their success, the wealthy come to believe that they are fundamentally better than other Americans and that working people deserve their declining fortunes. They trumpet meritocracy while ensuring that their children enjoy crushing advantages from birth. They have unprecedented access to politicians and use it to push policies that swell their wealth while defunding institutions, such as public education, that sustain opportunities for less-fortunate Americans.

"The Crisis of the Middle-Class Constitution: Why Economic Inequality Threatens Our Republic," by Ganesh Sitaraman (Knopf )

What does the Constitution have to do with all this? Two things. First, it’s part of the problem. Shortly before his appointment to the Supreme Court in 1972, Lewis Powell Jr. recommended that business interests launch an effort to influence the courts. And they did, with a vengeance. Money flowed into “public interest” litigation campaigns promoting corporate rights and undermining consumer and labor protections. The Supreme Court’s ruling in Citizens United, striking down limits on corporate political spending, is but one of many recent decisions invalidating restrictions on corporate power.

Far more important, however, Sitaraman argues that the Constitution can — indeed must — be part of the solution. He suggests that extreme economic inequality conflicts with the Constitution. This is the book’s main contribution, and it is more than worth the read. To make his point, Sitaraman, an associate professor at Vanderbilt Law School, takes us on an entertaining tour of constitutional history from ancient times to the present. Economic inequality, it turns out, has been a central concern of constitutionalism from the outset. By the end of the tour, we see our Constitution in a different light; provisions that we never thought about before emerge from the shadows and assume a new importance.

The story begins in ancient Athens, with Plutarch complaining that the “disparity between the rich and the poor” had put the republic “in an altogether perilous condition.” From one side, the wealthy elite struggled to replace the republic with an oligarchy; from the other, the poor flirted with demagogues and would-be tyrants. (Sound familiar?) The same problem afflicted all of the ancient republics, including mighty Rome. After less than two decades of life under the republic, the Roman plebes were already so disgusted with patrician domination that they abandoned the city in the midst of a war and refused to fight. What to do? The solution, in Rome and elsewhere, was to enact what Sitaraman calls “class warfare” constitutions. Ancient constitutionalists conceded the inevitability of class conflict but sought to defuse it by giving both rich and poor representation in government. In Rome, for example, this took the form of the tribunate, an elected council of plebes endowed with veto power. Sitaraman concludes that, although the ancient republics were “in part built on the backs of women and slaves,” their class warfare constitutions did foster relative equality among citizens. Fast-forward more than a millennium, and we see the next great wave of republics, in medieval Italy, following the same pattern.

Then came a huge shift in thinking and a new kind of constitution. Looking back on the fall of the ancient and medieval republics, 18th-century political philosophers concluded that republican government could not survive without a measure of economic inequality. But instead of constitutionalizing class warfare, they sought to prevent the concentration of wealth that gave rise to class antagonisms in the first place. The English political philosopher James Harrington, for example, urged strict limits on the size of estates.

When the United States entered the picture, it produced the first real “middle class constitution” in history. The founders of the American republic agreed with Harrington that “equality of estates” fostered republican liberty, but they proposed no serious measures to limit property accumulation. Instead, they proclaimed that America was blessed with conditions that guaranteed equality, namely an open frontier and an abundance of land. “Many in the founding generation had internalized Harrington’s lessons,” Sitaraman contends, “and they believed that the American republic was built on America’s exceptional economic conditions — on the foundation of the middle class.”

We might wonder whether Sitaraman is overstating his claim. How can a constitution that contained no provisions to ensure middle-class power nevertheless be considered middle class? Sitaraman offers two answers. First, it is a middle-class constitution because, in practice, it has survived only by operating as one. In a series of dramatic confrontations over more than two centuries, Americans have repeatedly defended their republic against the twin dangers of plutocratic oligarchy and tyranny. Each time, Americans mobilized to restore what the framers had identified as the middle-class precondition for republicanism. Jacksonian Democrats abolished property qualifications for voting and slew the national bank. Abraham Lincoln and the Republican Party terminated not only chattel slavery but also its downward pull on free working people. The populists and progressives subdued the trusts and robber barons of the Gilded Age by enacting the progressive income tax, regulating business and curbing the flow of money into politics. Roosevelt’s New Dealers restrained Depression-era “economic royalists” with more economic regulation, enforced by administrative agencies. So successful were these reforms that America entered a “glorious” period of relative equality from 1945 through the 1970s, during which some women and people of color began to share in the nation’s prosperity.

Second, each of these struggles was framed in constitutional terms, and each produced constitutional change. Jackson vetoed the national bank on constitutional grounds. The 13th Amendment outlawed slavery and involuntary servitude, the 16th authorized the progressive income tax, the 17th ended the purchase of Senate seats, and the 24th abolished the poll tax. The New Deal yielded transformative Supreme Court decisions upholding business regulation and labor legislation. Put all this together, and you end up with a strong tradition of middle-class constitutionalism.

So how do we stave off the threat of plutocracy today? Sitaraman provides a useful catalogue of measures, most of them familiar. His main point is that we need long-term structural reforms, including breaking up the banks and rejuvenating industrial democracy, and not merely incremental policy shifts, such as returning to a more progressive tax structure or reviving campaign finance restrictions. Given that the wealthy currently dominate politics, how do we get there? Sitaraman points to the mobilization of social movements and — less happily — the possibility that a national emergency of some kind might disrupt politics-as-usual and create an opening for change.

Like any pathbreaking exploration of a topic, the book invites challenges from many directions. One wonders, for example, why Sitaraman chose a class schema (upper, middle, lower) that omits the working class. Given the choice, about 47 percent of Americans self-identify as working class, compared with 42 percent middle class. The most successful anti-oligarchical social movement of the industrial era — the workers’ movement — was not an undifferentiated middle-class movement; it thrived on the solidarities and power flowing from a structural position in the economy. (The same could be said of the populist movement, which arose out of agrarian distress.)

One might also wonder whether we actually had something of a class warfare constitution during Sitaraman’s “glorious years” of the 1940s through the 1970s. Although the law did not give unions a direct role in government, it did co-opt them into a system of industrial relations that assumed conflict between employees and employers. According to a study cited by Sitaraman, the decline of unions accounts for about half the increase in net income inequality from 1980 to 2010.

On the whole, however, the book succeeds in its central objective: presenting a strong case that economic inequality isn’t just a matter of fairness or economic efficiency; it’s about the survival of our constitutional order. Americans who value the republic can only hope that judges, legislators and we the people take heed.

Why Economic Inequality Threatens Our Republic

By Ganesh Sitaraman

Knopf. 423 pp. $28