A more thorough explanation:

Rules of change refer to the fundamental rules that govern how a legal system's other rules can be altered or repealed. This concept was introduced by legal theorist H.L.A. Hart.

In Hart's theory, a legal system's primary rules can be identified and changed through secondary rules. These secondary rules include rules of change, which prescribe the process for altering or repealing laws.

For example, in the United States, the Constitution serves as the primary legal document, while the legislative process serves as the secondary rule for changing laws. The Constitution outlines the process for amending it, which involves a proposal by two-thirds of both the House of Representatives and the Senate, followed by ratification by three-fourths of the states.

Another example is the process for changing traffic laws. The primary rule is the existing traffic law, while the secondary rule is the legislative process. If lawmakers want to change a traffic law, they must propose and pass a new law through the legislative process.

Overall, rules of change are essential for maintaining a functioning legal system and ensuring that laws can be updated and improved over time.