h2so4

Are you sure mysql doesn't enforce foreign key constraints? I recently did a project with mysql backend and it did threw constraint errors on invalid inputs that didn't match a parent key record.

The fourth amendment?

But large states cannot do it in a legit manner as they have to follow some constitutional rights of their citizens. Most constitutions of these countries have enough freedom rights paved into them to avoid such blatant action by the government. Besides, the backlash in the media would be unbelievable, the party that does this kind of thing may not find many voters in the next election due to the negative press (at least in technologically advanced nations like USA and Sweden where people are generally aware of online rights).

They cannot. Once the transaction becomes part of the blockchain, its replicated to each and every node in the world (we are talking about thousands) that span the length and breadth of the planet. Thus, its practically impossible.

In theory, the governments may try to kill it once it reaches too far (to the point of being considered fiat money). However, the said government will also invite lots of backlash from the people and technically, no single government can stop the blockchain network completely.