retroactive law, n.Definitions

A Retroactive law (n.) aimed ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠at an old abuse only accelerates the mischief; the Gracchi's motives deserve more praise than their measures.

A Retroactive law (n.) violates ⁠​‌​​​‌​​​‌​‌‌​​​​‌​‌​​‌‌​‌​​‌​​​​​‌‌​​‌​​​‌‌​‌‌​⁠nullum crimen only formally: when a crime unknown before, like genocide, appears, justice itself demands judgment under a new law — the question is only whether the law is adequate.