Great post!
On the other hand it'd be great to have a way to "invalidate" the stolen coins, that would only affect the thief that could not spend the coins anymore...
All the other coins would increase in value, so that's good for the community as a whole, even if it does not repay the people whom the coins were stolen from.
This invalidation/block could be optional of course.
I think if something like this could work, it would also reduce the potential issues in the future.
How to judge and who will judge? The court? Then why don't you simply use fiat?
Maybe each user could judge for himself?
Or maybe we could have blacklist plugins that can read list of "blacklisted coins", kind of like AdBlock Plus can get various list of Ads to filter. Then users would just opt in or out of these.
How do I refuse stolen fiat money? there is no way for me to know that any coin/bill is stolen... but with the blockchain it may be feasible.