Русско-англо-русский юридический словарь

The choice of use of "retroactive" or "retrospective" appears to be a matter of regional common usage of the English language, with no identifiable international distinctive use of either term. In both England and Wales and in Scotland preference is given widely to the use of "retrospective" rather than "retroactive" by both lawyers and politicians but with little formal distinction being made between the meanings of the terms. This appears true in Ireland as well. By contrast, in the USA the term "retroactive" is used (with a stress on the first syllable not present in European English usage) rather that "retrospective" (Questionnaire 'Retroactivity and Tax Legislation', EATLP 2010)

In countries where the 'rule of law' applies, there is usually a dislike of legislation which has retrospective effect. In this brief post, I do not seek to discuss in any detail the merits or otherwise of the arguments for or against retrospective legislation, save to say that with regard to legal certainty, it is important both for individual citizens and business enterprises as well as other legal entities that they can assess the legality and legal effects of a planned action before instituting such action. (legalweek.com)

Generally, Congress does not provide administrative agencies authority to create rules that have retroactive effect. (uslegal.com)