retroactivity
Noun
Meaning
The state or characteristic of being retroactive.
(law) The application of a law to events that took place before it was made.
Source: en.wiktionary.orgSynonyms
Examples
And remember, the SARA Act provided for retroactivity, probably one of the first statutes that did so,” Teixeira said the in the letter.
In his opening Statement at the International Military Tribunal, the British Chief Prosecutor Lord Hartley Shawcross stated: "There is thus no substantial retroactivity in the provisions of the Charter.