That foundation isn't particularly strong: https://en.wikipedia.org/wiki/Ex_post_facto_law

This is only a foundation in US law and even then only for criminal law.

Not only US. There are many other countries that forbid retroactive laws.

Money fuels politics (especially in the USA) and the media companies had money to spend. The average joe didn't care, so it was a perfect storm. That's less so nowadays, but mostly because even the companies are finding it hard to get bipartisan support for these kinds of things anymore.

> One of the foundations of law that you cannot make retroactive changes.

This is a common misconception, at least regarding laws in the US. While I may not agree with it, the US Supreme Court has for literally centuries (like since 1798) explicitly allowed all types of retroactive laws. Most importantly, the USSC has long held the prohibition against ex post facto laws only applies to criminal, not civil laws. (As an aside, this also shows what bullshit it is when justices say they are just "calling balls and strikes". Justices, of all political stripes, make up laws all the time. The Constitution, as written, very clearly and plainly says "No Bill of Attainder or ex post facto Law shall be passed." At some point - Calder v. Bull in 1798 to be exact - the Supreme Court decided it only applies to criminal law.)

Good info: https://www.law.cornell.edu/constitution-conan/article-1/sec... and https://supreme.justia.com/cases/federal/us/219/140/