How Roman Was the Constitution?

When Americans drafted their Constitution in 1787, they drew on centuries of political thought, including ideas from the Roman Republic. One particularly influential account came from the Greek historian Polybius, who argued that Rome's success depended on balancing different kinds of political power. Rome's consuls commanded armies and exercised executive authority, the Senate managed finances and advised magistrates, and popular assemblies elected officials and passed laws. No single institution could govern entirely on its own.

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The American system has some recognizable similarities, but also important differences. Rome elected two consuls annually, while the United States chose a single president serving a four-year term. Both republics had senates, although Rome's was an influential council of political elites rather than a legislative chamber like the American Senate. Rome's popular assemblies also operated differently from the House of Representatives. In the comitia centuriata, for example, citizens voted in groups organized partly by wealth, giving richer citizens disproportionate influence. American representatives, by contrast, were elected from geographical districts, although voting rights were initially restricted.

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How much of this resemblance was intentional? John Adams provides unusually direct evidence of American engagement with Roman political thought. In A Defence of the Constitutions of Government of the United States of America, he discussed Polybius's account of Rome and argued for balancing political power among different institutions. Yet American constitutional ideas also developed from British government, colonial experience, and Enlightenment political philosophy. Studying these connections led me to distinguish between institutions that happen to resemble one another and ideas whose influence can actually be traced through historical sources.