When legislation changes the common law, what is this referred to?

The correct term for when legislation changes the common law is referred to as derogation of common law. This concept represents the act of removing or altering the established legal principles that have been developed through judicial decisions over time. When legislation derogates from common law, it effectively supersedes or modifies those common law rules, making them no longer applicable in the face of the new statutory provisions. This is significant because it illustrates the dynamic nature of law, where statutory law can shape and redefine the framework within which legal matters are handled, providing clarity and modern relevance that may not be present in older common law precedents.