参考リンク: [1] 遡及効とは?意味・具体例・相続への影響までわかりやすく解説 | クラウドサイン: https://www.cloudsign.jp/media/sokyuko [2] 法の不遡及 - Wikipedia: https://ja.wikipedia.org/wiki/%E6%B3%95%E3%81%AE%E4%B8%8D%E9%81%A1%E5%8F%8A [3] The history of the principle of non-retroactivity: https://users.cecs.anu.edu.au/~James.Popple/publications/articles/retroactive/2.html [4] Non-Retroactivity as a General Principle of Law | Utrecht Law Review: https://utrechtlawreview.org/articles/10.36633/ulr.604 [5] 遡及効とは? 民法の具体例・契約におけるバックデートや ...: https://keiyaku-watch.jp/media/kisochishiki/sokyuko [6] Retroactivity - Restore Justice Foundation: https://restorejustice.org/legal-explainer/explainer-retroactivity