The U.S. Constitution has the second-most demanding amendment rules among 101 democratic constitutions reviewed by Pew Research Center, a barrier that helps explain why many proposed changes to American government rarely become constitutional amendments.
Congress must approve a proposed amendment by two-thirds votes in both the House and Senate, followed by ratification by three-quarters of the states — 38 of 50, according to Pew's analysis. The Constitution has been in effect for 237 years and has been amended 27 times.
How the comparison works
Pew used an amendment-difficulty classification developed by political scientist Donald S. Lutz. Where a constitution provides multiple amendment routes, the researchers scored its least difficult route, which they cautioned is not necessarily the route most often used in practice.
The review covered 101 democratic constitutions. Five other democracies were not scored because their constitutional rules are spread among statutes, precedents, customs or unwritten norms rather than a single codified text. That scope matters when interpreting the U.S. ranking: it is a comparison of formal amendment rules in the constitutions Pew scored, not a count of every country's actual amendments.
Only the Federated States of Micronesia ranked harder to amend. Pew said its easiest route requires two separate two-thirds votes in a 14-member legislature, approval by the president and support from three-quarters of voters in at least three of its four states.
Palau, Switzerland and Australia also have difficult amendment rules, with approval required at both national and state levels. At the other end of Pew's comparison, many countries with one legislative chamber can amend their constitutions through a process closer to passing ordinary legislation, though with a larger majority.
What the ranking means for U.S. proposals
Pew noted that its surveys have found broad support for changes such as term and age limits for officials and campaign-finance restrictions. The analysis did not provide field dates, sample sizes or percentages for those surveys, and support for an idea does not itself satisfy the separate congressional and state ratification thresholds.
The short analysis was published ahead of Constitution Day on Sept. 17 and is drawn from a broader July 2026 comparison of American democracy with other countries. Its ranking concerns the constitutional process, not whether any particular U.S. proposal should be adopted.
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