retroactivity

From retroactive + -ity.

retroactivity (usually uncountable, plural retroactivities)

1. The state or characteristic of being retroactive.
2. (law) The application of a law to events that took place before it was made.
   • 1994 May 6, Todd Purdum, “New Yorkers in Congress at War With a Lawyer”, in The New York Times‎^[1], archived from the original on 3 February 2023:

     Should the legislation pass with the retroactivity provision, the firm's percentage would apply to the amount already due the states; if not, it would apply to the amount they collect over the next 12 years.

   • 2008, Ben Juratowitch, Retroactivity and the Common Law, page 12:

     it must be pointed out that the distinction between retroactivity and retrospectivity, while describing a real difference in the verbal form in which retrospective law is expressed, lacks normative and practical significance.

• retroactiveness