Both Ethereum's Proof of Work and Proof of Stake designs assume that block producers are financially rational, but does not assume block producers to be benevolent. There is one exception however, and it is when block producers choose the gas limit of a block where it is assumed that block producers care about the long term health and decentralisation of the chain. Indeed, the block gas limit is one of the only parameters in Ethereum that is not dictated by node consensus, but instead is chosen by block producers. This decision was initially made to allow urgent changes in the block gas limit if necessary. Both drastically increasing or decreasing this parameter could have serious consequences that may not be desired. It is therefore a critical parameter that should require node consensus to avoid any sudden harmful change imposed by a small number of actors on the rest of the network.
As of `FORK_BLOCK_NUMBER`, the `header.gasLimit`**MUST** be equal to `BLOCK_GAS_LIMIT`, where `BLOCK_GAS_LIMIT` is a hardcoded constant set to `12,500,000`.
While it would be possible to remove the `gasLimit` field from block headers, it would change the data structure to be hashed, which could lead to unintended consequences. It is therefore easier to leave the gasLimit as part of block headers.
The `12,500,000` value is being proposed as it's the current block gas limit as of time of writing this EIP. The actual amount could be altered with a subsequent EIP to avoid deviating from the core intent of this EIP.
## Backwards Compatibility
This EIP is backward compatible.
## Security Considerations
Rapid changes to the gas limit will likely be more difficult to execute, which could be problematic if an urgent situation arise that required changing the gas limit.
## Copyright
Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
