The Constitution wasn't in effect in 1782, and nobody was condemned and imprisoned by the Massachusetts decision. Rather the opposite. People were effectively freed.
Whether anything was really taken away from the slaveowners isn't really clear-cut either. If former slave and former slaveowner were both amenable to staying together and the former slave doing the same work in exchange for room and board, that was possible. It was the deprivation of freedom that was ended.
You are attempting to strawman me here. "ex post facto" has a known connotation in terms of constitutional law, and it means "creating a law after the fact."
The courts are creating law. That is not their job. They are usurping powers they do not rightfully possess. It is a bad thing when courts create law, especially when they do it with deliberate trickery or twisting the intent of legislators.
The Constitution wasn't in effect in 1782, and nobody was condemned and imprisoned by the Massachusetts decision. Rather the opposite. People were effectively freed.
So making up fake law is okay provided all the right people like the result? Why have laws then? Why not just have a popularity contest?
Your thinking undermines the rule of law. You are okay with this because you like the result. I like the result too, but I absolutely abhor creating fake law through courts.
Whether anything was really taken away from the slaveowners isn't really clear-cut either. If former slave and former slaveowner were both amenable to staying together and the former slave doing the same work in exchange for room and board, that was possible. It was the deprivation of freedom that was ended.
In practice what actually happened is the Massachusetts slave owners immediately took their slaves to other slave states and sold them so as not to lose their investment.
I'm sure some were freed as a result of this court decision, but I would think most were not.