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retroactivity; retroaction; being retroactive (to)
法律の遡及適用は原則として禁止だ。
Retroactive application of law is prohibited in principle.
給与の改定が四月に遡及された。
The salary revision was made retroactive to April.
遡及して税金を徴収する措置が取られた。
Measures were taken to collect taxes retroactively.