[_delirium]

Isn't that difficult to enforce, unless you also blacklist the public mixers? It's easy to launder moderate amounts of Bitcoins through the mixers, after which blacklisting the original wallets would no longer impede the money being spent. Though if the major mixers were willing to go along with such a blacklist it'd get considerably more effective.

[microcolonel]

You can track the amount through the transaction logs though, and mixers don't want to get stuck with bitcoins which will eventually be invalidated by other parts of the ecosystem.

Not a perfect idea at this point though, it'd require considerable organization to get this done, certainly better than throwing away Bitcoin or waiting for it to become criminalized. IMHO