Rigid legislation – this is a specific type of legislation, which requires either a concrete body of Parliament to amend or change it, or requires a specific quorum for such a purpose. For example, many countries accept legal rules that their constitution may be changed only in certain conditions, where there are three-fourths of the members of the Parliament who vote to agree with it.

The term origins of the word “rigid”, which literally means “fixed, stable, unmovable”.