It is a law that changes consequences of actions committed before the law was inacted. It may make things better or worse. it is sometimes not permitted with common laws.
The legal term for a law that has criminal penalties that effect people prior to the enactment of that law is called an "ex-post facto law". Ex-post facto laws are illegal in most countries and the US Constitution expressly forbids the creation or passage of an ex-post facto law.
ex post facto law
The term is "Ex Post Facto"
ex post facto ex post facto
I believe it's "ex post facto."
ex post facto
Ex-Post Facto
I think you mean ex post facto, which is latin for "after the fact" I think you mean ex post facto, which is latin for "after the fact"
Ex post facto laws are specifically prohibited by the Constitution.
"Ex post facto"
Ex Post Facto law "Congress shall pass no Ex Post Facto law", I believe is how it appears in the constitution. It is latin for after the fact.
That would be making a law retroactive to a date before the passing of the law. The US Constitution forbids doing it. That would be known as an Ex Post Facto Law and is unconstitutional.