BIP 91 Activation Nears as Mining Enforcement Begins

Around July 18, 2017, BIP 91 was approaching full activation as miners who had signaled support began preparing to enforce the requirement that all blocks must signal SegWit readiness. Under BIP 91's rules, once locked in, miners would reject blocks that didn't signal for SegWit, effectively making SegWit signaling mandatory for miners who wanted their blocks to be accepted by the majority of hashpower.

This enforcement mechanism was designed to quickly push signaling to the 95% threshold required for full SegWit activation under the original BIP 141, making the August 1 UASF deadline irrelevant by ensuring SegWit locked in through the original activation mechanism.

The approaching BIP 91 enforcement represented sophisticated game theory in action. By coordinating among themselves to reject blocks from non-signaling miners, the majority of hashpower could force universal SegWit signaling without requiring a contentious fork. Any miner who continued refusing to signal would find their blocks orphaned and would lose revenue, creating strong economic incentive to comply even for miners who had previously opposed SegWit.

This mechanism demonstrated how Bitcoin's consensus rules could be changed through strategic coordination among miners and economic actors without requiring changes to Bitcoin Core software or formal governance processes.The success of BIP 91 would prove that Bitcoin's rough consensus model could work even in highly contentious situations, though it would also raise questions about the relative power of different stakeholders in Bitcoin's governance structure and whether similar coordination mechanisms could be used to force through changes in the future.