I think you need to elaborate on this. Law enforcement can enforce the things they have power over, like putting someone in jail. But they do not have power over the blockchain and they cannot reverse a transaction.
Governments can put a blockchain account/UTXO on a sanctions list and make it a crime to accept payments directly or indirectly funded from that account.
To my knowledge, this hasn't happened yet, but I strongly suspect that it's only a question of time. Embargoes/sanction lists are one of the most powerful mechanisms of law enforcement for governments – I doubt that they will continue to let cryptocurrencies undermine that for too long.
It's a tool, but not a silver bullet. Mixers exist, for example. But that's not even the main point. The key holder has the ultimate power to simply throw away the key. There is no recourse for that.
> It's a tool, but not a silver bullet. Mixers exist, for example.
Definitely, but I don't think that mixers would be considered an acceptable "excuse" for dubious coin origin.
> The key holder has the ultimate power to simply throw away the key. There is no recourse for that.
True, but what is the utility of that?
Not talking about coin origin are we.
I suppose the point is to not have something seized from you which you do not want taken.
Anyway, these questions are now outside of/unrelated to common sense understanding of what a "finalized" payment is.
If you truly believe that, I don't think you understand how law enforcement works.