So the rule of law is predicated on laws being known, transparent, clear, and knowable in particular to those that will be sanctioned pursuant to those laws. Retrospectively applied legislation breaches all of those central tenets of the rule of law. To be punished, in particular, in the criminal justice context by law that was not in place, that was not knowable at the time that you committed the act, is one of the most fundamental breaches of the rule of law. The might of the State is supposed to be brought into line by our principles of lawmaking and, indeed, by our robust human rights laws.