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].[1]

The Pew analysis evaluated 101 democratic constitutions globally to measure the friction built into their amendment processes [1]. 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 [1]. 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].[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 [1]. 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].[1]

The comparative framework relies on a classification scheme originally developed in 1994 by the late political scientist Donald S. Lutz [1]. 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 [2]. "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 [2].[1][2]

Where a country's constitution provides multiple routes for an amendment, the Pew researchers scored the easiest available option [1]. They noted that this theoretical baseline represents the "least difficult" path, which may not always be the route most frequently employed in practice [1]. Even using this most forgiving metric, the U.S. system's baseline requirements outpace nearly every other democracy on Earth [1].[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 [1]. If it survives the federal legislature, it must then be ratified by 38 of the 50 state legislatures [1]. 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].[1]

At the opposite end of the spectrum, the data shows that many democracies allow constitutional changes with significantly less friction [1]. 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].[1]

Furthermore, five democracies were excluded from the scoring entirely because they rely on "uncodified" constitutions [1]. 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 [1]. Because there is no single text to amend, the Lutz scoring system cannot mathematically evaluate their rigidity [2].[1][2]

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 [2]. 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].[1][2]

While the Lutz index provides a rigorous comparative baseline, the data carries inherent limitations [3]. The scoring measures the formal difficulty of the written rules, not the actual frequency of constitutional change achieved through other means [3]. 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].[1][3]