I think the issue with that could be that if the act for which they were sentenced becomes legal then it can be a bit dubious to hold someone in prison over it. For example places where homosexuality was criminal and has since been legalized.
That requires the legislature to create a new law pardoning everyone who was sentenced and not selectively pardoning high-profile people, like in the US.
This would be blatantly unconstitutional for crimes like treason. Legalizing treason is possibly the most unconstitutional a law can be.
I think the issue with that could be that if the act for which they were sentenced becomes legal then it can be a bit dubious to hold someone in prison over it. For example places where homosexuality was criminal and has since been legalized.
That requires the legislature to create a new law pardoning everyone who was sentenced and not selectively pardoning high-profile people, like in the US.
This would be blatantly unconstitutional for crimes like treason. Legalizing treason is possibly the most unconstitutional a law can be.