Retroactivity; the act of applying a law, rule, or decision to a time before its enactment. A legal/official term often used in phrases like 'retroactive effect' or 'retroactive application'.
新しい税法の遡及は企業に大きな影響を与える可能性がある。
The retroactivity of the new tax law could have a major impact on companies.
裁判所はこの条例の遡及を認めなかった。
The court did not recognize the retroactive application of this ordinance.