It's both: it's a bug fix, whose side effect is a hard fork. The whole point of a blockchain is that there is no single authority that can unilaterally impose

It's both: it's a bug fix, whose side effect is a hard fork. The whole point of a blockchain is that there is no single authority that can unilaterally impose "law" by fiat. In practical terms, the software used by the majority of clients is "law", but it's entirely possible for forked and non-forked chains to coexist: for example, Ethereum Classic is a pre-fork version of Ethereum, and Bitcoin Cash is a fork of Bitcoin. https://en.wikipedia.org/wiki/Ethereum_Classic https://en.wikipedia.org/wiki/Ethereum_Classic https://en.wikipedia.org/wiki/Bitcoin_Cash https://en.wikipedia.org/wiki/Bitcoin_Cash