The concept of 'natural justice' includes the notion that procedural rules can be made retroactive.

Natural Justice

A legal philosophy aimed at ensuring fairness in judicial, administrative, and decision-making processes, including the right to a fair hearing.

Procedural Rules

Standards and regulations guiding the processes and proceedings of courts or administrative bodies.

Retroactive

Pertaining to a law, amendment, or decision that takes effect from a date in the past, affecting actions or agreements that occurred before it was made.