term:

Retrospective

retrospective adj

: affecting things past
: retroactive
;specif
: of, relating to, or being a law that takes away or impairs vested rights, creates new duties or obligations, or attaches new disabilities with respect to acts and transactions completed before its enactment
ret·ro·spec·tive·ly adv

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.