The U.S. Constitution Is the Second-Hardest to Amend in the Democratic World

To change the foundational rules of a democracy, a proposed amendment must clear a specified mathematical threshold of consensus—a binding constraint designed to separate enduring principles from transient political moods. In the United States, that threshold currently requires two-thirds of both chambers of Congress and three-quarters of state legislatures.

Whether that condition can hold in a highly polarized era is increasingly doubtful, effectively freezing the text in place. According to a new data analysis released on September 14, 2026, by the Pew Research Center, the U.S. Constitution is now mathematically among the most rigid governing documents in the world.[1]

The Pew analysis evaluated 101 democratic constitutions globally to measure the friction built into their amendment processes. The data reveals a stark comparative reality: "Of all 101 democratic constitutions we examined, the U.S. Constitution has the second-most onerous amendment process," the researchers concluded. The only nation with a higher barrier to constitutional change is the Federated States of Micronesia, a former U.S. trust territory in the South Pacific with roughly 76,000 inhabitants.[1]

Micronesia's process illustrates the extreme end of constitutional rigidity. To amend its foundational text, the nation requires two separate two-thirds votes in a 14-member legislature, explicit approval by the president, and the support of three-quarters of voters in at least three of its four states. While the U.S. does not require a national popular referendum or presidential approval, its dual-level legislative requirements place it just behind Micronesia in formal difficulty.[1]

The comparative framework relies on a classification scheme originally developed in 1994 by the late political scientist Donald S. Lutz. Published in the American Political Science Review, Lutz's index quantified the difficulty of amendment by scoring the specific hurdles—legislative supermajorities, referendums, and sub-national ratifications—required to alter a text. "Variance in amendment rate is due largely to the interaction of a constitution's length and the difficulty of its amendment process," Lutz wrote in his foundational paper.[1][2]

Where a country's constitution provides multiple routes for an amendment, the Pew researchers scored the easiest available option. They noted that this theoretical baseline represents the "least difficult" path, which may not always be the route most frequently employed in practice. Even using this most forgiving metric, the U.S. system's baseline requirements outpace nearly every other democracy on Earth.[1]

The mechanics of the U.S. process explain its extreme score. An amendment must first secure a two-thirds supermajority in both the House of Representatives and the Senate. If it survives the federal legislature, it must then be ratified by 38 of the 50 state legislatures. This dual-level requirement—demanding overwhelming consensus at both the national and state levels—is shared by the other nations at the top of the difficulty index, including Palau, Switzerland, and Australia.[1]

At the opposite end of the spectrum, the data shows that many democracies allow constitutional changes with significantly less friction. Countries operating with unicameral, or single-chamber, legislatures often permit constitutional amendments through a process that closely mirrors the passage of ordinary legislation, requiring only a larger parliamentary majority rather than sub-national ratification or public referendums.[1]

Furthermore, five democracies were excluded from the scoring entirely because they rely on "uncodified" constitutions. In these systems, such as the United Kingdom, governance rules are distributed across various statutes, legal precedents, customs, and unwritten norms rather than a single entrenched document. Because there is no single text to amend, the Lutz scoring system cannot mathematically evaluate their rigidity.[1][2]

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The evidence pack highlights a core tension in constitutional design: the interaction between a document's length and its rigidity. Longer constitutions tend to require more frequent updates to manage specific policy details, while shorter, framework-style documents like the U.S. Constitution rely on broad principles. The U.S. text has been in effect for 237 years but has been formally amended just 27 times, reflecting both its brevity and its high barriers to change.[1][2]

While the Lutz index provides a rigorous comparative baseline, the data carries inherent limitations. The scoring measures the formal difficulty of the written rules, not the actual frequency of constitutional change achieved through other means. In systems where the formal amendment process is functionally locked, the burden of constitutional evolution often shifts to the judiciary. The practical consequence of this extreme rigidity is a growing disconnect between public consensus and constitutional law, as popular reforms like term limits remain mathematically improbable to codify.[1][3]