retrospective

adjective | \ ˈre-trə-ˌspek-tiv \ | ret·ro·spec·tive

1. : affecting things past : retroactive; specifically : 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 : 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