How does a rigid constitution differ from a flexible constitution?

In the study of constitutional law, the distinction between rigid and flexible constitutions centers on the process required to amend them.1

• Rigid Constitutions: These stipulate that at least some parts of the document cannot be modified using the same procedures required to enact ordinary statutory law. Because they often require complex, lengthy, or supermajority processes for amendments, they are generally more difficult or slow to change. The U.S. Constitution is a primary example, requiring supermajorities for both proposal and ratification.12
• Flexible Constitutions: These allow constitutional rules to be modified or abrogated through the simple legislative process used for ordinary statutes. Consequently, they are relatively easier to amend. The constitution of the United Kingdom is considered flexible, as its rules can be changed by an act of Parliament.31

While rigid constitutions can provide institutional controls to protect fundamental principles, they do not inherently guarantee stability, as constitutional meaning often evolves through judicial or legislative interpretation. Conversely, flexible systems can maintain continuity through broad societal consensus on political values rather than institutional obstacles.1