Good old fashioned investigation. It would just take one government demanding it's businesses to subscribe to their blacklist and it would be done automatically. It could even be implemented by companies to segregate their Blockchain network.
the miners could be made to comply as well, a full p2p network mining protocol would prevent this since 99% of the network would have to agree to exclude certain transactions.
Would you mind explaining the "segregate their Blockchain network" thing a little deeper for me? I'm having trouble wrapping my brain around it.
you can control within the blockchain the coins that you process, buy 1 bitcoin divide it into a thousand pieces and internally within the business mark it as worth 10,000 dollars. This is good to do between company divisions, so no one starts asking the IT department for outlandish requests or the Engineering department for that matter. Just internal accounting audits. only the coins marked by the company are valid to have that value.
All the coins have the same source, the original coin, so it's progression and movement can be tracked to see how costs move through the corporation and how effective they are at maximizing their budget internally. Once in a while you may lose a couple fragments(employees using it to purchase snacks accidentally) but it will be invalidated immediately since the companies blockchain explorer will notice the discrepancy and inform that the coin has gone out of network circulation( it has gone to a non approved payment address.)
This can be further enhanced using a side-chain that updates the blockchain every so many transactions... there by giving the company a gap to reverse any transactions that have occurred with-in their network before it becomes permanently transcribed in the main Bitcoin ledger.
In this system, original, freshly created coins are immeasurably more valuable than used coins.