[comex]

> The difference in Proof of Stake is a lawsuit could force the distributor of the software to change the hash to one where coins weren’t stolen.

And with proof of work a lawsuit could force the distributor to change the consensus rule so that a particular transaction is invalid - just as Ethereum did voluntarily with the original DAO.

> You mention “POW forks”, but Bitcoin’s POW has never been hard forked

Instead it’s been soft forked, which turns the consensus rules into a popularity contest. If a soft fork produces two competing branches of the blockchain, old clients will go with whichever branch has more mining power. Which means you open yourself up to interesting attacks like convincing 51% to literally steal the funds of the other 49% (which is much worse than a mere double spend). Or, more realistically, in the case of a contentious soft fork that ends up roughly fifty-fifty, you could ‘just’ end up on a different side of the fork from the people you want to transact with. Either way, soft forks don’t make the downsides of policy changes go away.

[ricardolopes]

Changing consensus rules requires coordinating a fork. This requires coordinating developers, miners and node operators. That may fly in pseudo decentralised chains where the community accepts whatever the leader says so, and even so, at high risk. In bitcoin, for instance, where there is no leader, this would never be a viable scenario.

Soft forks don't force you to download and run new clients just to be able to use the network, which is an important difference. You can use your existing client, you just don't have the new features and don't run validations on them.

The greatest risk on soft forks is that chain split you mention. That's why any reasonable soft fork deployment requires a long time window with a large majority of hashrate signaling support (like 95%).

[DennisP]

Changing a PoS checkpoint would also require coordinating a fork. Even if a dev team were forced to make the change, they couldn't make everyone go along with it.